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1.
The high frequency of speciation events associated with species flocks (i.e., radiations of closely related species) provides
invaluable insight into the speciation process. Investigations of the speciation process in the marine environment are rare,
and therefore, the genetic analysis of the rockfish genus Sebastes, considered an ancient marine species flock, provides an opportunity to investigate this process in the sea. Using both mitochondrial
and nuclear markers, we analyzed five closely related species within the rockfish subgenus Sebastosomus. Our goal was to understand the evolutionary history and genetic relationships among species within this group and to provide
evidence of recent speciation events within the subgenus. In the genetic analysis of the subgenus, we found different stages
of the speciation process, with greater genetic divergences among three of the five species, evidence of recent divergence
between two of the five species, Sebastes entomelas and S. mystinus, and significant genetic divergence between two lineages within S. mystinus revealing a signature of incipient speciation. We also found frequency differences of the two S. mystinus lineages among sample locations and found no evidence of introgression between the lineages at the location where both coexist.
Although Sebastes is an example of an ancient species flock, this study provides evidence of ongoing speciation within the genus and reveals
stages of this process from incipient to distinct species. 相似文献
2.
Peter D. Dijkstra Ole Seehausen Boye L. A. Gricar Martine E. Maan Ton G. G. Groothuis 《Behavioral ecology and sociobiology》2006,59(5):704-713
It has been suggested that sympatric speciation can be driven by sexual selection on male mating traits alone. However, a
fundamental problem for this process is the lack of ecological differentiation that would stabilize the coexistence of incipient
species through frequency-dependent selection. Such selection can also occur if male aggression is primarily directed towards
similar rather than towards dissimilar phenotypes, so that rare male phenotypes would enjoy a negatively frequency-dependent
fitness advantage. We experimentally tested such an aggression bias in two recently diverged, ecologically and anatomically
similar sympatric cichlid species pairs of the genus Pundamilia from Lake Victoria. Territorial males of a pair of partially reproductively isolated species with red and blue nuptial coloration,
respectively, studied in the laboratory were confronted simultaneously with both colour types enclosed in transparent tubes.
Red males were more aggressive to red stimuli under white light but not when colour differences were masked under green light.
Blue males were equally aggressive to both stimuli in both light conditions. Males of two apparently fully reproductively
isolated species, again one with red and one with blue nuptial coloration, studied in the field, both directed more aggressive
behaviour towards conspecific than towards heterospecific stimulus males. The differential allocation of aggression would
create an advantage for males of the less abundant phenotype or species, thereby potentially supporting stable coexistence
of the phenotypes. The finding that this effect was less clear in the partially reproductively isolated species pair than
in the fully isolated species pair is discussed. 相似文献
3.
Summary Changes in territorial behavior of blackchinned hummingbirds (Archilochus alexandri) in response to experimental changes in territory quality were investigated using artificial feeders and simultaneous, pair-wise observations of owners. Some of the responses of A. alexandri were similar to those documented by a previous study of the Anna's hummingbird (Calypte anna): A. alexandri defending rich territories spent more time on their territories, encountered a greater percentage of intruders, and chased more intruders than did A. alexandri defending poor territories. In contrast to C. anna, A. alexandri supplemented chases with energetically inexpensive threat vocalizations more extensively when territory quality was increased. This difference may be related to A. alexandri's more tenuous control of rich territories. When both species were observed on very poor territories, A. alexandri chased a greater percentage of intruders, consumed a greater proportion of available food, and obtained a greater net energy gain from their territories. When observed simultaneously on territories with ad lib food, both species defended highly exclusive territories but A. alexandri suffered higher intrusion pressure and spent more time and energy in defense. These interspecific differences in territorial behavior may facilitate sympatric coexistence of the two species through aggressive partitioning of flower patches according to productivity: the greater payoff received by C. anna on rich territories and A. alexandri on poor territories should favor a corresponding monopolization of rich areas by C. anna and poor areas by A. alexandri. 相似文献
4.
Gabriele Gerlach Andrea Hodgins-Davis Bradley MacDonald Rebecca C. Hannah 《Behavioral ecology and sociobiology》2007,61(11):1765-1770
Zebrafish (Danio rerio) larvae prefer the olfactory cues of kin to non-kin. We examined the potential benefits of kin preference by comparing growth
rate, shoaling, and aggressive behavior in juvenile zebrafish housed in groups of either familiar kin or unfamiliar non-kin.
Over an observation period of 5 days, the animals grew 33% more in kin groups; however, neither shoaling nor the frequency
of aggressive interactions was different in groups of related versus unrelated individuals. Shoaling behavior increased with
increasing observation time and increasing age, while aggressive behavior remained the same. We conclude that associating
with kin probably creates a less stressful environment that allows for higher growth rates, which can lead to higher direct
fitness based on increased survival and earlier reproduction. Kin recognition leading to kin-structured groups may therefore
be under positive selection. 相似文献
5.
Barbara A. Han Paul W. Bradley Andrew R. Blaustein 《Behavioral ecology and sociobiology》2008,63(2):241-250
Behaviors have evolved in response to various selection pressures over evolutionary time. However, not all behaviors are adaptive.
Some presumably “ancient” behaviors, persistent for millions of years, may be detrimental in the face of novel selection pressures
in modern times. These pressures include a multitude of emerging infectious diseases which may be stimulated by environmental
changes. We examined how a globally emerging amphibian pathogen, Batrachochytrium dendrobatidis (BD), affected two key evolutionarily persistent behaviors displayed by amphibian larvae: aggregation and thermoregulation.
Larval aggregation behavior is often essential for foraging, thermoregulation, and antipredator defense, but varies among
species. Thermoregulatory behavior speeds larval development in ephemeral habitats. Specifically, we examined whether aggregation
and thermoregulatory behaviors changed when exposed to the BD pathogen in two species (Bufo boreas and Rana cascadae) whose larvae aggregate in nature. In laboratory choice tests, larvae of neither species avoided infected conspecifics. BD-exposed
B. boreas larvae aggregated, while unexposed R. cascadae larvae associated more frequently with BD-exposed conspecifics. There was no evidence of behavioral fever or altered thermoregulation
in larvae of four species we examined (Pseudacris regilla, Rana aurora, B. boreas, R. cascadae). The absence of behavioral fever may suggest an inability of the larvae of some host species to mediate infection risk by
this pathogen. Thermoregulatory behaviors may exhibit a high degree of evolutionary inertia in amphibian hosts because they
are linked with host physiology and developmental rates, while altered aggregation behaviors could potentially elevate pathogen
transmission rates, leading to increased infection risk in social amphibian species. 相似文献
6.
The emergence of the Isthmus of Panama, approximately 3.0-3.5 million years ago, established two very different marine systems (the Caribbean and the eastern Pacific) and separated previously continuous marine populations. The geographic isolation of transisthmian sister species provides an excellent basis for the study of divergence and speciation processes. Here we describe the morphology of the first postembryonic stage of Alpheus saxidomus and A. simus, two rock-boring alpheids; the estimated time since divergence for this transisthmian pair ranges from 4.4-6.1 to 3-9 million years. The presence of a first zoeal stage in A. saxidomus, e.g., without pleopods and a telson with 7+7 setae, indicates a prolonged developmental sequence. In contrast, hatchlings of A. simus are substantially more developed and resemble juveniles. Thus, the developmental modes of A. saxidomus and A. simus are strikingly different with abbreviated, most probably direct, development in the latter species. Reduced food availability in the Caribbean compared to the Pacific coast is likely to be a possible reason for the evolution of such important differences in life history traits of the two transisthmian sister species. It is suggested that a transition from prolonged to abbreviated development evolved gradually during the estimated time since divergence; however, such a shift may have taken place within a substantially smaller time span. 相似文献
7.
Residency status of individuals in populations may be an important determinant of the outcomes of interspecific competition
between native and introduced species. We examined direct behavioral interactions between two similarly sized rodents, the
alien Rattus rattus and native Rattus fuscipes when they were respective residents and intruders in a small enclosure. Resident individuals were dominant in their behaviors
toward intruders irrespective of the species that was resident. In contrast, interactive behaviors between conspecifics were
often neutral or amicable, supporting suggestions that R. rattus and R. fuscipes are social animals. We then tested whether rodent species use heterospecific odors to avoid aggressive competitive interactions
and partition space in the field. Neither R. fuscipes nor R. rattus responded to traps scented with the odors of male or female heterospecifics. If R. fuscipes does not recognize the odor of introduced R. rattus, then odors will not be cues to the presence or territorial space of competing heterospecifics. Rather, findings from both
enclosure and field trials suggest that direct aggressive interactions between individual R. rattus and R. fuscipes probably facilitate segregation of space between these two species in wild populations, where resident animals may typically
be the winners and exclude heterospecific intruders. These findings have implications for the invasion success of introduced
rodents such as R. rattus into intact forests, where native populations may have competitive advantage because of their residency status. 相似文献
8.
Bo Terning Hansen Lars Erik Johannessen Tore Slagsvold 《Behavioral ecology and sociobiology》2007,61(8):1203-1209
Imprinting plays a key role in the development of species recognition, with young imprinting upon the morphological characters
of their parents. However, the potential role that cultural transmission might play in species recognition remains largely
uninvestigated. Great tits (Parus major) and blue tits (Cyanistes caeruleus) do not normally perceive each other as sexual competitors or potential partners. However, after reciprocal interspecific
cross-fostering, both species may perceive individuals of the foster species as potential rivals or mates. Although the experience
of being raised by heterospecifics clearly has affected the species recognition of cross-fostered birds, some of them breed
naturally with conspecifics. The offspring of such cross-fostered birds (OCF) are hence raised by parents that look like ordinary
conspecifics but display deviant species recognition as compared to controls in terms of aggressive response towards rivals.
Comparing the aggressive behavior of OCF, cross-fostered birds and controls towards territorial intruders may thus help tease
apart the influence of morphological vs behavioral cues of parents in the development of offspring species recognition. To
this end, we compared birds from all three treatments with respect to their aggressive response to territorial intruders of
both species during the breeding season. OCF and controls did not differ in their pattern of response towards heterospecific
and conspecific stimuli. Compared to cross-fostered birds, OCF and controls showed less aggression towards heterospecific
intruders, while the response towards conspecific intruders did not differ between treatments. These results demonstrate that
both tit species imprint on the morphological characters of their parents, but that parental behavior is not important for
the development of species recognition in terms of aggressive response towards territorial intruders. 相似文献
9.
Studies of reef fish herbivory have mainly focused on the impacts and behaviour of adults of tropical species. In this study,
the ontogenetic shifts in home range, aggression, feeding rate, diet and gut morphology in juveniles and adults of two temperate
territorial damselfishes, Parma microlepis and Parma unifasciata, were determined. Both P. microlepis and P. unifasciata juveniles under 80 mm TL exhibited no aggressive chases towards conspecifics or other species, while above 80 mm TL aggressive
chase frequency increased in conjunction with an increase in home range, defended as a territory. Ontogenetic diet shifts,
characterised by an increase in herbivory (P. unifasciata: juveniles: 64% plant material, adults: 95% plant material; P. microlepis: juveniles: 43% plant material, adults: 67% plant material) were observed for both species. The ratio of digestive tract
length to body length, which often accompanies a switch to herbivory, increased significantly with ontogeny for both species.
Compared to tropical confamilial grazers, these temperate damselfish species feeding rates were lower, and they had larger
territories which were not as strongly defended (fewer aggressive chases). 相似文献
10.
Direct male-male competition can facilitate invasion of new colour types in Lake Victoria cichlids 总被引:2,自引:2,他引:0
Peter D. Dijkstra Ole Seehausen Ton G. G. Groothuis 《Behavioral ecology and sociobiology》2005,58(2):136-143
The possibility that disruptive sexual selection alone can cause sympatric speciation is currently a subject of much debate. The initial difficulty for new and rare ornament phenotypes to invade a population, and the stabilisation of the resulting polymorphism in trait and preference make this hypothesis problematic. Recent theoretical work indicates that the invasion is facilitated if males with the new phenotype have an initial advantage in male-male competition. We studied a pair of sympatric incipient species of cichlids from Lake Victoria, in which the red (Pundamilia nyererei) and blue males (P. pundamilia) vigorously defend territories. Other studies suggested that red phenotypes may have repeatedly invaded blue populations in independent episodes of speciation. We hypothesised that red coloration confers an advantage in male-male competition, assisting red phenotypes to invade. To test this hypothesis, we staged contests between red and blue males from a population where the phenotypes are interbreeding morphs or incipient species. We staged contests under both white and green light condition. Green light effectively masks the difference between red and blue coloration. Red males dominated blue males under white light, but their competitive advantage was significantly diminished under green light. Contests were shorter when colour differences were visible. Experience of blue males with red males did not affect the outcome of a contest. The advantage of red over blue in combats may assist the red phenotype to invade blue populations. The apparently stable co-existence of red and blue incipient species in many populations of Lake Victoria cichlids is discussed.Communicated by C. St. Mary 相似文献
11.
V. Brock 《Marine Biology》1979,54(2):149-156
Habitat selection of two bivalve species, Cardium edule (L.) and C. glaucum (Bruguière) is described for sympatric and allopatric populations of both sibling species. It is demonstrated that C. edule grows faster than C. glaucum and is absent from localities with periodic low food-availability. The ability to burrow of C. glaucum is low compared with that of C. edule; the former species does not occur in very loose, well-sorted sand near the coast. Earlier studies which suggest that tidal range determine the species distribution could not be confirmed. 相似文献
12.
Some territorial animals exhibit a form of social recognition, commonly termed the "dear enemy effect", in which territory residents display lower levels of aggression toward familiar neighbors compared to unfamiliar individuals who are non-territorial "floaters". Despite the widespread occurrence of territorial social systems and use of acoustic signals for communication in anuran amphibians, only two previous studies have demonstrated vocally mediated dear enemy behavior in a territorial frog. In this study, I conducted neighbor-stranger discrimination playback experiments in a third species of territorial frog, the strawberry dart-poison frog, Dendrobates pumilio (Anura, Dendrobatidae). In the first experiment (n=24), I broadcast the calls of a subject's nearest neighbor and the calls of an unfamiliar individual from the approximate midpoint between the subject's and the neighbor's territories. Although males responded to the stimuli, they did not exhibit differential responses to the calls of neighbors and strangers. In a second experiment (n=22), I broadcast the calls of a neighbor and a stranger to subjects through a speaker located in the approximate center of the neighbor's territory. Males also responded to the playback, although less intensely than in the first experiment, but no discrimination between the calls of neighbors and strangers was found. Thus, territorial males of the strawberry dart-poison frog appear not to discriminate behaviorally between the advertisement calls of neighbors and strangers. Several proximate and ultimate-level hypotheses for this lack of vocally mediated neighbor-stranger discrimination are discussed.Communicated by T. Czeschlik 相似文献
13.
Charlotte Curé Thierry Aubin Nicolas Mathevon 《Behavioral ecology and sociobiology》2010,64(11):1823-1837
Hybridization between two closely related species breeding in sympatry depends on the effectiveness of both inter-sex (sexual
attraction) and intra-sex (competitors’ repulsion) components of communication. As birds primarily communicate acoustically,
several studies have investigated interspecific vocal interactions between the sexes and their consequences on sympatric zones
with a focus on songbird species. Here, we investigate these issues on intra-sex vocal interactions occurring during incubation
in two non-songbird sister species, the Yelkouan Puffinus yelkouan and the Balearic Puffinus mauretanicus shearwaters. We compared the acoustical structure of calls and the behaviors obtained in response to same-sex Yelkouan and
Balearic calls across allopatric parental populations from each species and a sympatric-hybridized population. Acoustic analyses
showed that, for both sexes, calls have species-specific characteristics while hybrids have intermediate acoustic features
compared to their parental species. Playback experiments showed that despite their vocal differences, both species interact
and reply to each other. Remarkably, incubating Yelkouan and hybrid individuals resulted in equal intra-sex responses to either
species while incubating Balearic birds led to lower territorial responses to Yelkouan than to conspecific calls. Moreover,
incubating Balearic males less readily responded to same-sex Yelkouan calls than Balearic females. These results may have
fitness consequences: Yelkouan birds, and especially males, would be more likely to win same-sex disputes against Balearic
incubating birds than against Yelkouan incubating birds. 相似文献
14.
The reproductive cycles and abundance of the sympatric colonial ascidians Pycnoclavella brava, Pycnoclavella aurilucens and Pycnoclavella communis from two Northwestern Mediterranean sites over a period of 2.5 years are reported. The species showed some differences in
their biological patterns. Gonad maturation and larval brooding took place during autumn and early winter for P. communis, during spring for P. aurilucens and during late winter and spring for P. brava. Summer was found to be the unfavorable season for all species, and an aestivation period occurred in P. communis and P. brava. Maximum abundance for the three species was observed during winter. Growth rates of the most abundant species, P. communis, were also monitored and found to peak during the initial phases of reactivation after aestivation. Growth rates decreased
afterwards, becoming negative as water temperature started to increase after the winter minima. Reproductive activity and
growth rates for P. communis displayed a temporal lag that suggested partitioning of resources to either reproduction or growth in this species. 相似文献
15.
Howard H. Whiteman John D. Krenz Raymond D. Semlitsch 《Behavioral ecology and sociobiology》2006,60(1):52-61
The study of reproductive isolation as a prerequisite to sympatric speciation has been limited by the focus on species that
have already experienced such isolation. However, a complete understanding of how such processes evolve depends on observing
taxa before they complete the speciation process. We studied the potential for sexual isolation in the polyphenic mole salamander,
Ambystoma talpoideum, using a series of laboratory and field experiments. This species consists of aquatic paedomorphic adults and terrestrial
metamorphic adults which are exhibited by both sexes and which mate in the same aquatic habitat. Previous field studies on
this species suggested that intermorph breeding would be less common during the winter months, because paedomorphic adults
begin breeding in early autumn and thus may have less energy available for reproduction in the winter. Laboratory experiments
conducted during the winter showed that the mating behavior of paedomorphic males occurred at a much lower frequency than
that of metamorphic males. In contrast, field experiments that best mimicked natural conditions revealed symmetric intermorph
breeding and included multiple paternity shared among males of each morph. This and other studies suggest that there is little
evidence of sexual isolation among morphs based on behavioral interactions alone. However, the potential for partial isolation
still occurs because of temporal and spatial differences in the frequencies of each morph in nature. Our results suggest that
further studies on this system, and other similar polyphenisms, may provide valuable insight into the mechanisms that underlie
the evolution of reproductive isolation. 相似文献
16.
Female choice and male–male aggression are two modes of sexual selection that can lead to elaboration of male morphological
and behavioral traits. In lek-mating species, male mating success is often strongly skewed, and it is puzzling why variation
in male traits is still observed given directional female choice. If male traits correlated with reproductive success are
honest signals of male quality, there may be survival costs associated with the expression of those traits. In this study,
we examined whether morphological, behavioral, and territorial traits are correlated with male mating success and survival
in the lek-mating greater prairie-chicken (Tympanuchus cupido). We introduce a novel application of multinomial discrete choice models for analysis of female mate choice behavior. We
found that behavioral and territorial attributes showed 6.5 times more variability among males than morphological traits.
Both display and aggressive behaviors were strong predictors of male mating success, suggesting that both female choice and
male–male aggression were important in determining mating success among male greater prairie-chickens. Moreover, annual survival
of male prairie-chickens was independent of mating success and male traits. Females appear to be choosing males based on behavioral
traits where large variation exists between males (coefficient of variation >30%). Behavioral traits were the most important
factor in determining mating success of male prairie-chickens, but the mechanism underlying this relationship is unknown.
In the future, experimental manipulations of male hormones or parasite loads could bridge the proximate mechanisms and ultimate
consequences of factors mediating male mating success in lek-mating grouse. 相似文献
17.
Debra K. Hoffmaster 《Behavioral ecology and sociobiology》1985,16(4):349-353
Summary Nearest-neighbor distances and species' densities were calculated for 949 individuals of 8 species of orb-weaving spiders from eight edge and meacow sites in Panama. These data were used to test the hypothesis that interspecific aggressive interactions influenced spider community structure by: (1) eliminating or decreasing the densities of sympatric, less aggressive species, or, (2) affecting nearest-neighbor relationships so that large or aggressive individuals had smaller, less aggressive or more distant neighbors. Although there was a negative relationship between the densities of two species pairs (Leucauge sp. and Mangora pia; Eriophora fuliginea and Cyclosa caroli), overall spider densities could not be predicted from indices of spider aggression obtained by introduction experiments. The spatial distribution of spiders in three dimensions was not significantly different than random. I attributed the lack of clumping to the relative vegetational homogeneity of my sites; the lack of overdispersion may reflect the fact that websites are not limiting. Relationships between nearest neighbors generally supported the aggression hypothesis, however, comparisons of the actual data with equivalent randomly-assorted data indicate that a hypothesis of randomly chosen neighborsis equally applicable. This result suggests that, unless websites differ significantly in their quality, with high quality websites in short supply, spider aggression may not affect community structure. 相似文献
18.
F. S. McEuen 《Marine Biology》1988,98(4):565-585
Spawning behaviors observed from May 1981 through August 1983 in the laboratory and field are described and compared for twelve species of northeast Pacific holothuroids collected from waters of the San Juan Archipelago, Washington. For many species, elevation of the anterior end, stretching of the introvert, tentacle waving, and swaying are behaviors commonly associated with gamete release. Less common activities include waving of introvert podia, waves of body wall contractions, errant males, aggregations, and pseudocopulation. Positively buoyant eggs of four species [Psolus chitonoides Clark, Cucumaria miniata (Brandt), C. piperata (Stimpson), and C. fallax (Ludwig)] were packaged in pellets, ropes, or strands and released passively; a female Molpadia intermedia (Ludwig) discharged negatively buoyant eggs in a single explosive burst. Two externally brooding sea cucumbers [C. lubrica (Clark) and C. pseudocurata Deichmann] produced strands of dilution-resistant sperm that were carried by currents to nearby females. Three species commonly sympatric [P. chitonoides, C. miniata, and Eupentacta quinquesemita (Selenka)] in high-current rocky habitats have overlapping spring breeding seasons, but spawn at different hours of the day.Please address all requests for reprints to Dr. McEuen at the Harbor Branch Oceanographic Institution 相似文献
19.
Male ornamentation is assumed to have evolved primarily from selection by female mate choice. Yet this is only one possible
reason for ornament evolution. Ornaments might also be useful in aggressive competition by improving opponent assessment between
males, or they might function to enhance signal detection by making males more conspicuous in the environment. We tested both
these ideas in territorial Anolis lizards in which female choice is either absent or secondary to males competing for territories that overlap female home
ranges. Male tail crests only evolved in species in which territory neighbors were distant, consistent with the signal detection
hypothesis. Once the tail crest had evolved, however, it seems to have become a signal in itself, with variation in the frequency
and size of tail crests within species correlating with variables predicted by the aggressive competition hypothesis. Our
study presents an apparent example of a male ornament in which the selection pressure leading to variation among species in
ornament expression is different from the selection pressure acting on variation within species. The Anolis tail crest is therefore likely to be an exaptation. We caution that conclusions made on the evolution of male ornaments are
dependent on the phylogenetic perspective adopted by a study. Studies restricted to single species are useful for identifying
selection pressures in contemporary settings (i.e., the current utility of traits), but may lead to erroneous conclusions
on the factors that initially lead to the origin of traits. 相似文献
20.
Symbion americanus was recently described as the second species in the phylum Cycliophora, living commensally on the American commercial lobster
Homarus americanus. A previous genetic analysis of American and European populations of cycliophorans suggested that haplotype divergence in
S. americanus was much greater than in its European counterpart S. pandora. This study examined the population structure and demographics of 169 individuals thought to belong to S. americanus collected from lobsters over 13 North American localities (Nova Scotia, Canada to Maryland, USA) between October 2003 and
January 2006. Cytochrome c oxidase subunit I sequence data clearly suggested the presence of three cryptic lineages in a species complex, often co-occurring
in the same lobster specimens. One of these lineages, named the “G” lineage, was represented by very few individuals and therefore
was excluded from subsequent statistical analyses. The other two sympatric lineages, named the “T” and “C” lineages, showed
different population structure and demography. Although limited geographic structure was found in the T lineage, the C lineage
showed higher nucleotide and haplotype diversity values, as well as more variation between localities. The data also indicated
that the T lineage underwent a recent population expansion, suggesting that the C and T lineages may have speciated in allopatry
but a subsequent population expansion may have been responsible for their current sympatric distribution. Studies on the anatomy
and ecology of the sympatric lineages of this species complex should provide further information on the identity of the holotype
of S. americanus, which currently cannot be ascribed to any of the three cryptic lineages. 相似文献