The Phylogeography and Population Demography of the Yunnan Caecilian (Ichthyophis bannanicus): Massive Rivers as Barriers to Gene Flow

Ichthyophis bannanicus is the only caecilian species in China. In this study, the phylogeography and population demography of I. bannanicus were explored, based on the mitochondrial DNA genes (cyt b and ND2) and 15 polymorphic microsatellite loci. Altogether 158 individuals were collected from five populations in Yunnan province, Guangxi province, Guangdong province, and Northern Vietnam. Phylogeographical and population structure analysis identified either two groups (Xishuangbanna, Northern Vietnam-Yulin-Yangchun-Deqing) or three groups (Xishuangbanna, Northern Vietnam-Yulin-Yangchun, and Deqing), indicating that the Red River and Pearl River systems may have acted as gene-flow barriers for I. bannanicus. Historical population expansion that happened 15–17 Ka ago was detected for mtDNA data and was possibly triggered by warmer weather after the Last Glacial Maximum. However, the Bayesian simulations of population history based on microsatellite data pinpointed population decline in all populations since 19,123 to 1,029 years ago, demonstrating a significant influence of anthropogenic habitat alteration on I. bannanicus.     

Migrations of Fish Juveniles in Dammed Rivers: the Role of Ecological Barriers

Journal of Ichthyology - Analysis of previously published characteristics of the downstream migration of juvenile cyprinids (Cyprinidae) and percids (Percidae) from the Volga and Ivankovskoe,...     

Primate Behavior Studies: Essential to Primate Welfare

A special session of the 2006 Animal Behavior Society annual meeting

In Memory of Sylvia Taylor, DVM     

Primate sexual swellings as coevolved signal systems

Many female catarrhine primates possess visually conspicuous organs that apparently function to increase the sexual interest of adult male conspecifics around the time the female is ovulating—i.e. sexual swellings. The hypothesized functional benefits for both sexes of these sexual swellings are reviewed (honest signaling; paternity confusion; paternity confidence and paternal investment; protection; incitement of precopulatory male-male competition; and postcopulatory sexual selection), as well as an additional hypothesis that has not yet been applied to this problem (sensory exploitation). Currently available evidence is presented that supports or fails to support each of these hypotheses. Predictions associated with broad groupings of these hypotheses, which could be tested in noninvasive field studies, are then presented. Ecological circumstances are discussed that could have led to differential mating success among female primates, and hence to sexual selection on females and directional evolution of sexual swellings. It is concluded that the available evidence does not support the paternity confidence-paternal investment hypothesis; that the paternity confusion hypothesis lacks empirical support, but could still be viable; and that insufficient data exists at present to rigorously test the other hypotheses. The ecological factors that may have led to differential reproductive success among females as a function of mating frequency or mate choice likewise require further empirical investigation.     

Primate Sociality to Human Cooperation

Developmental psychologists identify propensities for social engagement in human infants that are less evident in other apes; Sarah Hrdy links these social propensities to novel features of human childrearing. Unlike other ape mothers, humans can bear a new baby before the previous child is independent because they have help. This help alters maternal trade-offs and so imposes new selection pressures on infants and young children to actively engage their caretakers’ attention and commitment. Such distinctive childrearing is part of our grandmothering life history. While consequences for other cooperative activities must surely follow, the novel rearing environments set up by helpful grandmothering can explain why natural selection escalated preferences and motivations for interactivity in our lineage in the first place, and why, unlike other aspects of infant development, social sensitivities are not delayed in humans compared with genus Pan.     

Using Adeno-associated Virus as a Tool to Study Retinal Barriers in Disease

Müller cells are the principal glial cells of the retina. Their end-feet form the limits of the retina at the outer and inner limiting membranes (ILM), and in conjunction with astrocytes, pericytes and endothelial cells they establish the blood-retinal barrier (BRB). BRB limits material transport between the bloodstream and the retina while the ILM acts as a basement membrane that defines histologically the border between the retina and the vitreous cavity. Labeling Müller cells is particularly relevant to study the physical state of the retinal barriers, as these cells are an integral part of the BRB and ILM. Both BRB and ILM are frequently altered in retinal disease and are responsible for disease symptoms.There are several well-established methods to study the integrity of the BRB, such as the Evans blue assay or fluorescein angiography. However these methods do not provide information on the extent of BRB permeability to larger molecules, in nanometer range. Furthermore, they do not provide information on the state of other retinal barriers such as the ILM. To study BRB permeability alongside retinal ILM, we used an AAV based method that provides information on permeability of BRB to larger molecules while indicating the state of the ILM and extracellular matrix proteins in disease states. Two AAV variants are useful for such study: AAV5 and ShH10. AAV5 has a natural tropism for photoreceptors but it cannot get across to the outer retina when administered into the vitreous when the ILM is intact (i.e., in wild-type retinas). ShH10 has a strong tropism towards glial cells and will selectively label Müller glia in both healthy and diseased retinas. ShH10 provides more efficient gene delivery in retinas where ILM is compromised. These viral tools coupled with immunohistochemistry and blood-DNA analysis shed light onto the state of retinal barriers in disease.     

Primate models to study eccrine sweating

The histochemistry and histology of the eccrine sweat gland in the rhesus monkey (Macaca mulatta) are described. The histochemical distribution and localization of enzymes and substrates are very similar to those found in the human; innervation is cholinergic. Active eccrine glands on the general body surface average 136 glands/cm². Above the thermal neutral zone (TNZ), sweating is the major avenue for heat loss and the role of panting in dissipating heat is relatively insignificant. The intrahypothalamic administration of prostaglandin E₁ (PGE₁) suppresses sweating and leads to an increase in core temperature. A linear relation is found between local sweat rates on the general body surface and clamped hypothalamic temperature. Studies also provide direct support for the concept that brain temperature and skin temperature interact additively in the control of sweating in higher primates. The functional characteristics of eccrine sweating in the patas monkey (Erythocebus) are qualitatively similar to those in the rhesus monkey. The patas monkey maintains a relatively constant rectal temperature (37.6–38.4°C) when equilibrated to a wide range of ambient temperaures of 15–40°C. Eccrine sweating is the main effector system for heat dissipation above the TNZ. We emphasize here that evaporative heat loss that is due to sweating is related to both mean skin and mean body temperature and at 40°C is 40% higher than that recorded from the rhesus monkey. These results indicate that the patas monkey, because of its high sweating capacity and other similarities with the human eccrine system, is a most appropriate animal model for comparative studies of eccrine sweat gland function in primates in general.     

Distribution Patterns of Tropical Plant Foods as an Evolutionary Stimulus to Primate Mental Development

Primates are noted for their mental abilities but the selective basis for such traits has remained obscure. It is hypothesized that the element of predictability associated with the spatial and temporal distribution patterns of plant foods in tropical forests has served to stimulate mental development in primates taking much of their food from the first trophic level. Primates able to remember the locations and phenological patterns of a wide variety of plant foods could move directly to such foods when and where available without wasting time and energy in random search. This would enhance overall foraging success by lowering procurement costs associated with a varied and patchily distributed plant diet. Membership in a cohesive social unit, that utilized the same supplying area over many consecutive generations, would also enhance foraging success by serving to transmit important information about diet to close kin. Data on the foraging behavior of howler and spider monkeys are presented to test certain implications of this hypothesis. Similar selective pressures, but applied to foods from the second trophic level, may have been of critical importance in the mental development of hominids . [primates, evolution, intelligence, plant foods, Aleles, Alouatta ]     

Primate species separation in relation to secondary plant chemicals

Food selection of different primate species is reviewed in relation to secondary plant chemicals such as alkaloids and tannins. Different species discriminate differently against these chemicals. The tolerance of potentially toxic substances (e.g. alkaloids) is not restricted to species with enlarged foreguts but is also found among lemurs with rather unspecialized digestive systems. On the community level different reactions towards food chemicals seem to be an important mechanism contributing to species separation and thus allowing coexistence.     

Primate brain architecture and selection in relation to sex

Background  

Social and competitive demands often differ between the sexes in mammals. These differing demands should be expected to produce variation in the relative sizes of various brain structures. Sexual selection on males can be predicted to influence brain components handling sensory-motor skills that are important for physical competition or neural pathways involving aggression. Conversely, because female fitness is more closely linked to ecological factors and social interactions that enable better acquisition of resources, social selection on females should select for brain components important for navigating social networks. Sexual and social selection acting on one sex could produce sexual dimorphism in brain structures, which would result in larger species averages for those same brain structures. Alternatively, sex-specific selection pressures could produce correlated effects in the other sex, resulting in larger brain structures for both males and females of a species. Data are presently unavailable for the sex-specific sizes of brain structures for anthropoid primates, but under either scenario, the effects of sexual and social selection should leave a detectable signal in average sizes of brain structures for different species.