Investigation of the Influence of Seagrass on Fisheries Catch Level Using Isotonic Regression

The relationship between seagrass area and the commercial catch of some economically important South Australian fish species is not known in any quantitative sense. However, there is evidence in the literature to suggest that seagrass decline will detrimentally impact on species abundance and composition, and consequently that the presence or absence of seagrass will compromise the commercial and recreational fishery. In this paper we describe the construction of models based on order restricted (isotonic) regression and discuss the role of seagrass area, in terms of its influence on the level of commercial catch through modifying the effect of fishing 'effort'.     

Effects of publication bias on conservation planning

Conservation planners need reliable information on spatial patterns of biodiversity. However, existing data sets are skewed because some ecosystems, taxa, and locations are underrepresented. We determined how many articles have been published in recent decades on the biodiversity of different countries and their constituent provinces. We searched the Web of Science catalogues Science Citation Index (SCI) and Social Science Citation Index (SSCI) for biodiversity-related articles published from 1993 to 2016 that included country and province names. We combined data on research publication frequency with other provincial-scale factors hypothesized to affect the likelihood of research activity (i.e., economic development, human presence, infrastructure, and remoteness). Areas that appeared understudied relative to the biodiversity expected based on site climate likely have been inaccessible to researchers for reasons, notably armed conflict. Geographic publication bias is of most concern in the most remote areas of sub-Saharan Africa and South America. Our provincial-scale model may help compensate for publication biases in conservation planning by revealing the spatial extent of research needs and the low cost of redoing this analysis annually.     

Seminal fluid enhances sperm viability in the leafcutter ant Atta colombica

The seminal fluid that accompanies sperm in ejaculates has been shown or suggested to affect sperm competition and paternity success of insects by preventing female remating, inducing oviposition, and forming mating plugs. In Atta leafcutter ants, queens have multiple mates but never remate later in life, although they may live and produce fertilized eggs for several decades. The mating biology and life history of these ants therefore suggests that the major function of seminal fluid is to maximize sperm viability during copulation, sperm transfer, and initial sperm storage. We tested this hypothesis by comparing the viability of testis sperm and ejaculated sperm (mixed with seminal fluid) and found a significant positive effect of seminal fluid on sperm viability. We further quantified this positive effect by adding accessory gland secretion (a major component of seminal fluid) in a dilution series, to show that minute quantities of accessory gland secretion achieve significant increases in sperm viability. Sperm stored by queens for 1 year benefited in a similar way from being exposed to accessory gland compounds after dissection in control saline solution. Our results provide the first empirical evidence that seminal fluid is important for the production of viable ejaculates and that the accessory glands of Atta males—despite their small size—are functional and produce a very potent secretion.     

Female grouping best predicts lekking in blackbuck (Antilope cervicapra)

The study of intraspecific variation can provide insights into the evolution and maintenance of behavior. To evaluate the relative importance of ecological, demographic and social conditions thought to favor lekking, I studied variation in mating behavior among and within populations of the blackbuck, Antilope cervicapra, an Indian antelope. Rather than viewing lekking as a discrete mating strategy, I took a continuous approach and treated lekking as a question of the clustering of mating territories, with leks representing one extreme in a range of territory distributions. I surveyed nine blackbuck populations, which differed in population density and in habitat conditions. For each population, I described the mating system in terms of the clustering of mating territories, and measured various factors suggested to favor lekking. I found that large-scale, among-population variation in territory clustering was most strongly related to female group size. Territory clustering was not related to population density. Female group size, in turn, was best explained by habitat structure. Interestingly, these among-population patterns were repeated at a finer spatial scale within one intensively studied population. These findings suggest that territorial males respond to local patterns in female distribution (represented by group size) when making decisions regarding territory location. Finally, although female distribution may explain territory clustering at the population level and more locally within a population, other selective factors (e.g., female preference, male competition, male harassment) are likely to shape the clustering and size of territories at even finer scales.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Communicated by T. Czeschlik     

The interrelationships between resource-holding potential,resource-value and reproductive success in territorial males: How much variation can we explain?

A long-standing hypothesis in behavioural ecology posits that males with greater resource-holding potential (RHP) control resource sites deemed more valuable by sexually-receptive females and, thereby, males controlling such sites accrue greater reproductive success (RS). This hypothesis has historically been investigated using three separate but non-mutually exclusive relationships (male RHP vs. resource value, resource value vs. male RS and male RHP vs. RS). The relationships between these three variables are predicted to be strongly positive, however, due to measurement error and biological noise, perfect correlations (r = 1.0) are rare in biology even for well-established relationships. Moreover, the inaccurate identification of either the male trait(s) important to RHP or the resource characteristic sought by females will weaken the observed strength of the relationships. Here, I use meta-analysis to quantitatively describe the general pattern of these relationships in animals. I predict that the relationships between male RHP, resource-value and RS should be significantly positive (male RHP and resource-value should explain a large amount of the variation in male RS). My meta-analysis supports this hypothesis; however, in the best case scenario only ca. 20% of the variation in the response variable was explained. I conclude by identifying areas in which we need to improve our investigations of resource-defence animals and recommending approaches to meet these needs. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Monitoring,imperfect detection,and risk optimization of a Tasmanian devil insurance population

Most species are imperfectly detected during biological surveys, which creates uncertainty around their abundance or presence at a given location. Decision makers managing threatened or pest species are regularly faced with this uncertainty. Wildlife diseases can drive species to extinction; thus, managing species with disease is an important part of conservation. Devil facial tumor disease (DFTD) is one such disease that led to the listing of the Tasmanian devil (Sarcophilus harrisii) as endangered. Managers aim to maintain devils in the wild by establishing disease‐free insurance populations at isolated sites. Often a resident DFTD‐affected population must first be removed. In a successful collaboration between decision scientists and wildlife managers, we used an accessible population model to inform monitoring decisions and facilitate the establishment of an insurance population of devils on Forestier Peninsula. We used a Bayesian catch‐effort model to estimate population size of a diseased population from removal and camera trap data. We also analyzed the costs and benefits of declaring the area disease‐free prior to reintroduction and establishment of a healthy insurance population. After the monitoring session in May–June 2015, the probability that all devils had been successfully removed was close to 1, even when we accounted for a possible introduction of a devil to the site. Given this high probability and the baseline cost of declaring population absence prematurely, we found it was not cost‐effective to carry out any additional monitoring before introducing the insurance population. Considering these results within the broader context of Tasmanian devil management, managers ultimately decided to implement an additional monitoring session before the introduction. This was a conservative decision that accounted for uncertainty in model estimates and for the broader nonmonetary costs of mistakenly declaring the area disease‐free.     

Solitary nesting as an alternative breeding tactic in colonial nesting bluegill sunfish (Lepomis macrochirus)

Colonial breeding can evolve in response to benefits afforded by clumped individuals, such as reduced predation and increased ease of assessing potential mates. However, colonial breeding can also impose costs such as increased disease transmission or increased cuckoldry. Here, we investigate solitary nesting as a potential alternative breeding tactic in colonial breeding bluegill sunfish (Lepomis macrochirus). Most male bluegill, termed parentals, compete for nesting sites in colonies and then court and spawn with females and provide sole care of the eggs. Although nesting in a colony results in reduced predation and fungal infection of broods, it comes at a cost of increased parasitism by specialized cuckolder males that do not nest. We found that 4.5% of parentals forgo spawning in a colony and instead construct nests solitarily. Solitary males were of similar size and age to colonial males, but were in significantly better condition. Solitary males obtained as many eggs as males nesting in the center of colonies, and significantly more than males nesting on the periphery of colonies. Thus, females do not appear to discriminate against solitary males. Solitary males had smaller ear tabs, a presumed sexually selected character used by parental males in intrasexual competition, than colonial males. Tracking data revealed consistency in nesting tactic (but not nest position within the colony) between spawning attempts. We suggest that solitary nesting represents either a facultative decision made by parental males in top condition at the onset of breeding, or a life history decision to forgo spawning in colonies.Communicated by K. Lindström     

Protein content of spermatophores in relation to monandry/polyandry in butterflies

The evolution of a mating system, and specifically mating frequency, is dependent on the costs and benefits to both sexes of mating once or several times. In butterflies, males transfer a spermatophore that contains both sperm and accessory gland products. Accessory gland substances contain nutrients which, in some species, females use to increase their reproductive output and longevity. Nutrients contained in these packaged ejaculates represent investment by males in reproduction. Consequently, the nutritional composition of spermatophores may vary depending on the mating system. There are two lines of arguments concerning the evolution of the nutrient content of ejaculates. One hypothesis argues that male nuptial gifts evolved in the context of certainty of paternity and ease of finding mates; thus spermatophores of polyandrous males (with lower certainty of paternity and greater ease of finding mates) should contain less protein than those of monandrous males, since more spermatophores are produced on average. The other hypothesis argues that polyandry evolved in the context of maximization of male transfer of nutrients to females, and hence spermatophores of polyandrous males should contain more protein than those of monandrous males. In an attempt to distinguish between these two hypotheses, we determined how protein content of ejaculates varied with the degree of polyandry in nine species of pierid and two species of satyrid butterflies. We found that both relative ejaculate mass and protein content increased with the degree of polyandry. Hence our results are consistent with the view that polyandry has evolved in the context of male transfer of nutrients to females, and provides another example of a male adaptation to multiple mating in butterflies.     

Extra-pair paternity and the opportunity for sexual selection in a socially monogamous bird (Dendroica petechia)

We used multi-locus DNA fingerprinting to characterise the genetic mating system of the socially monogamous yellow warbler (Dendroica petechia). Over 2 years there were no instances of brood parasitism, but 59% of families (n = 90) contained extrapair sired young and 37% of offspring (n = 355) were of extra-pair paternity. Most hypotheses for extra-pair mating in monogamous species assume a paternity benefit to extra-pair sires, and focus on the benefit(s) to females. However, the assumption of male benefit has been little tested. Among yellow warblers, known extra-pair sires were just as likely to be cuckolded as any male in the population, and there was at least one reciprocal exchange of extra-pair paternity. Nevertheless, among known extra-pair sires, the paternity gains from extra-pair paternity were, on average, greater than the losses in their own families. These results show there is a paternity benefit to certain males. However, the benefit is not absolute but relative and therefore more difficult to measure. The results also suggest that patterns of extra-pair fertilisation are not determined by female choice alone. Most confirmed extra-pair mates were territorial neighbours, but some resided as far as three territories apart, and greater spatial separation was implied in other cases. Thus, the opportunity for extra-pair mating is great. We estimate that as a result of extra-pair fertilisations, variance in male mating success is increased somewhere between 3-fold and 15-fold over that which would result from within-pair reproduction alone. These findings affirm the potential importance of extra-pair reproduction for sexual selection in monogamous species and they support earlier suggestions that extra-territorial forays by male yellow warblers are for the purpose of extra-pair mating.