High diversity of deep-sea Gromia from the Arabian Sea revealed by small subunit rDNA sequence analysis

Gromia is a large marine protist with filose pseudopodia and ovoid test, common in coastal intertidal and sublittoral waters. Although deep-water Gromia-like morphospecies were discovered in the 1990s, their relations to the shallow water species have never been established. Moreover, very little is known about the diversity within Gromia, reflecting the fact that these morphologically relatively simple protists have few characters useful for species identification. Consequently, we have analysed the SSU rDNA and ITS rDNA genes to examine gromiid diversity in two different areas located on the Oman and Pakistan margins of the Arabian Sea (water depths 1,000–2,000 m). In total, 27 deep-sea gromiid sequences of the SSU rDNA gene and six sequences of the ITS rDNA region were obtained. Our data confirm that Gromia-like protists from the bathyal deep sea are related to the shallow-water gromiids. Within Arabian Sea Gromia, we identified seven distinctive lineages, five of which form a monophyletic group branching as a sister group to shallow-water species. Six lineages of Arabian Sea Gromia can be defined morphologically, while one lineage includes specimens that look identical to specimens from two other lineages. This indicates that each Gromia lineage represents probably a separate species and suggests that deep-sea gromiid diversity is higher than indicated by their simple morphology.     

Adaptive sex allocation by brood reduction in antechinuses

Antechinuses (Dasyuridae: Marsupialia) exhibit dramatic interpopulation variation in the sex ratio at birth, a pattern which has previously been interpreted in terms of both local resource competition and Trivers/Willard effects. However, Antechinus stuartii usually fail to wean all the young that attach to their teats. At least in captivity, this is because they often eat their young. In free-living populations, brood reduction affects sons and daughters differently. Mothers virtually always wean some daughters. The probability that a daughter will be weaned declines with the number of daughters in the pouch. The health or quality of the mother does not affect the number of daughters weaned. By contrast, mothers tend to wean all or none of their sons. A strong correlate of infanticide against sons is senescence. Old mothers rarely invest in sons, and produce low-quality daughters. Mothers suffer a direct cost (mortality during lace lactation) of male-biased litters. Coupled with data on prenatal sex allocation, these results support the conjoint influence of local resource competition and the Trivers-Willard effect. However, they suggest that in populations where females are largely semelparous, the population optimum generated by local resource competition may be unattainable, because of the importance of producing at least one daughter. These observations support recent theoretical claims that the sex ratio at the population level is not easily predicted, but suggest that the diversity of mammalian sex allocation tactics has been underestimated.     

Responses of pikas (Ochotona princeps,Lagomorpha) to naturally occurring terrestrial predators

Summary The responses of individually marked pikas (Ochotona princeps) to terrestrial predators were investigated in 1980 and 1981 in the Rocky Mountains of Colorado. Pikas uttered short call vocalizations in a variety of contexts: preceding or following an individual's movement, and in response to conspecifics, other nonpredaceous mammals and predators. Adult pikas apparently discriminated contexts in which predators were present by short calling more frequently and for longer duration compared with calling in nonpredator contexts. Short calls uttered by juveniles were similar in all contexts.Adults responded differently to two types of terrestrial predators: weasels and pine martens. Pikas called less frequently in response to weasels than to martens and avoided weasels more often than martens. They delayed the initiation of calling following the first sighting of a weasel more often than to martens. Weasels were determined to be more effective predators of pikas than martens, and these asymmetries in behavior and alarm vocalizations may indicate that responses reduce an individual's risk of predaton by weasels.Both male and female pikas called in response to predators, and residents called more often than nonresidents. The possible function of predator-related vocalization in pikas is discussed. It is suggested that calls to predators may function to warn local residents, which in pikas are usually closely related.