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Sexual selection and natural selection are evolutionary processes that shape the way a species behaves and looks over time. Scientists continue to provide evidence that natural selection not only occurred in the past but is continuing to shape species today. Demonstrating selection in the wild is always difficult and it is made even more so when the subject of the study is an animal as large (and difficult to measure) as the western gorilla (Gorilla gorilla). Fortunately, these massive pri........ Read more »
Breuer T, Robbins AM, Boesch C, & Robbins MM. (2012) Phenotypic correlates of male reproductive success in western gorillas. Journal of human evolution, 62(4), 466-72. PMID: 22386152
Researchers at the University of California, Santa Cruz, who pioneered the use of satellite tags to monitor the migrations of elephant seals have compiled one of the largest datasets available for any marine mammal species, revealing their movements and diving behavior at sea in unprecedented detail.
...A female elephant seal carries GPS tags that will monitor its location, swim speed, and depth and duration of dives.
...A new study published May 15 in the journal PLoS ONE focuses on the ann........ Read more »
Robinson, P., Costa, D., Crocker, D., Gallo-Reynoso, J., Champagne, C., Fowler, M., Goetsch, C., Goetz, K., Hassrick, J., Hückstädt, L.... (2012) Foraging Behavior and Success of a Mesopelagic Predator in the Northeast Pacific Ocean: Insights from a Data-Rich Species, the Northern Elephant Seal. PLoS ONE, 7(5). DOI: 10.1371/journal.pone.0036728
Scientists at the University of British Columbia and the Smithsonian Institution have discovered a sensory organ in rorqual whales that coordinates its signature lunge-feeding behavior – and may help explain their enormous size (Figure 1).
...Scientists dissect tissue samples from the chin of a fin whale in Iceland.
...Rorquals are a subgroup of baleen whales – including blue, fin, minke and humpback whales. They are characterized by a special, accordion-like blubber layer that........ Read more »
Pyenson, N., Goldbogen, J., Vogl, A., Szathmary, G., Drake, R., & Shadwick, R. (2012) Discovery of a sensory organ that coordinates lunge feeding in rorqual whales. Nature, 485(7399), 498-501. DOI: 10.1038/nature11135
Why do some primates have boldly colored faces while other species exhibit only a monotone color with little pattern? Facial color patterns likely serve several functions in primates, including intraspecific communication, species recognition, and possibly ecological or physiological roles as well (Figure 1). One hypothesis is that facial color patterns are used primarily for species recognition, with more subtle color variations used to assess individual identity.
...Higher facial color ........ Read more »
Santana, S., Lynch Alfaro, J., & Alfaro, M. (2012) Adaptive evolution of facial colour patterns in Neotropical primates. Proceedings of the Royal Society B: Biological Sciences, 279(1736), 2204-2211. DOI: 10.1098/rspb.2011.2326
Naked mole-rats (Heterocephalus glaber) have received a lot of scientific attention because they are the only mammals with a eusocial mating system. Like honey bees, naked mole-rats have colonies with a single breeding “queen,” a few breeding males, and numerous non-breeding “workers” who forage and maintain the complex burrow system. It is not surprising then, that these unusual mammals have received the lion’s share of attention from scientists.
As fascinati........ Read more »
Lövy, M., Šklíba, J., Burda, H., Chitaukali, W., & Šumbera, R. (2012) Ecological characteristics in habitats of two African mole-rat species with different social systems in an area of sympatry: implications for the mole-rat social evolution. Journal of Zoology, 286(2), 145-153. DOI: 10.1111/j.1469-7998.2011.00860.x
Many people believe that an important difference between humans and other animals is language--that what has brought us from fields and forests to our comfortable homes is our ability to communicate effectively with one another. And so the discovery that humans are not alone in their power of conversation is one that affects our definitions of our selves, and one opens many research opportunities for scientists.
Research into the calls made by bottlenose dolphins (Tursiops truncatus) at sea........ Read more »
Quick, N., & Janik, V. (2012) Bottlenose dolphins exchange signature whistles when meeting at sea. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2011.2537
Placental mammals, including some rodents and many bat species, enter torpor to conserve energy when ambient temperatures fall and food becomes scarce. Prolonged torpor is characterized by highly reduced body temperature and metabolic rates. Torpor is less common in mammals from the southern hemisphere. In fact, only one marsupial is known to undergo a seasonal hibernation, the mountain pygmy-possum (Burramys parvus).
Now, James Turner and his colleagues from the University of New Engl........ Read more »
Turner, J., Warnecke, L., Körtner, G., & Geiser, F. (2011) Opportunistic hibernation by a free-ranging marsupial. Journal of Zoology. DOI: 10.1111/j.1469-7998.2011.00877.x
The destruction of the World Trade Towers by terrorists on September 11th 2001 was just such an event. It goes without saying that there were many consequences for humans, including two wars, increased airline screening, and shifts in the political landscape. But there were also consequences for other mammalian species as well.
Endangered North Atlantic right whales (Eubalaena glacialis) gather during the late summer on calving grounds in the Bay of Fundy, Canada (Figure 1). A substantia........ Read more »
Rolland, R., Parks, S., Hunt, K., Castellote, M., Corkeron, P., Nowacek, D., Wasser, S., & Kraus, S. (2012) Evidence that ship noise increases stress in right whales. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2011.2429
By contributing writer Sarah Buckleitner
It is difficult for humans to imagine that a world of color and sound exists outside of the one that we can perceive, but for some organisms that world is a reality. Usually these animals aren't ones that we can readily relate to; bats and dolphins are two examples that both possess the ability to hear and emit high-frequency sounds. And so the discovery that a fellow primate, the Philippine tarsier (Tarsius syrichta), may have the ability to emit s........ Read more »
Migratory birds make refueling stops at one or more locations along their route. These stopover sites are critical; they provide food rich environments where birds can rapidly regain depleted fat stores before continuing their long treks. Likewise, several species of North American vespertilionid bats make long, north-south migrations each year. Silver-haired bats (Lasionycteris noctivagans) are a case in point. ... Previous research suggested that silver-haired bats make stopovers before........ Read more »
McGuire, L., Guglielmo, C., Mackenzie, S., & Taylor, P. (2012) Migratory stopover in the long-distance migrant silver-haired bat, Lasionycteris noctivagans. Journal of Animal Ecology, 81(2), 377-385. DOI: 10.1111/j.1365-2656.2011.01912.x
Modern whales include baleen whales (Mysticeti) and toothed whales (Odontoceti). Baleen whales are large, filter feeding whales that do not echolocate. Odontocete whales tend to be smaller in size, predatory, and are capable of producing high-frequency sounds used in echolocation. In addition, modern odonotcetes have an asymmetrical skull, where the bones of the skull roof extend posteriorly (telescoped) and are shifted to the left side of the skull (asymmetry) (Figure 1). This pronounce........ Read more »
Fahlke, J., Gingerich, P., Welsh, R., & Wood, A. (2011) Cranial asymmetry in Eocene archaeocete whales and the evolution of directional hearing in water. Proceedings of the National Academy of Sciences, 108(35), 14545-14548. DOI: 10.1073/pnas.1108927108
Golden moles (Chrysochloridae) are members of the mammalian Order Afrosoricida, an African group that also includes then tenrecs of Madagascar. Golden moles and true moles (Talpidae) evolved their fossorial habits independently. ... Scientists working with golden moles noticed that their silky fur often appears slightly iridescent (Figure 1).
...A Grant’s golden mole (Eremitalpa granti) showing it’s silky fur and leathery nose patch.
...Iridescence is common among insect and ........ Read more »
Snyder, H., Maia, R., D'Alba, L., Shultz, A., Rowe, K., Rowe, K., & Shawkey, M. (2012) Iridescent colour production in hairs of blind golden moles (Chrysochloridae). Biology Letters. DOI: 10.1098/rsbl.2011.1168
Biologists are well aware of the trade offs between reproduction and survival for r versus K selected species. Theory predicts that r-selected species grow quickly, produce more offspring at a time, exhibit minimal parental care, and have relatively short lifespans. In contrast, K-selected organisms produce relatively few offspring at a time, have longer lifespans, and provide more parental care. Thus, these species tend to live in stable environments where they reproduce multiple times ov........ Read more »
Turbill, C., Bieber, C., & Ruf, T. (2011) Hibernation is associated with increased survival and the evolution of slow life histories among mammals. Proceedings of the Royal Society B: Biological Sciences, 278(1723), 3355-3363. DOI: 10.1098/rspb.2011.0190
Scientists agree that domestic dogs evolved from wolves (Canis lupus, Figure 1), but disagree on when and where that domestication event took place. Archaeological evidence suggests that humans domesticated wolves 10-15,000 years ago in Eastern Europe and/or the Middle East. This evidence is based on canid remains that look like domestic dogs found in association with human remains. In contrast, mitochondrial DNA and autosomal single nucleotide polymorphism (SNP) data from a large sample o........ Read more »
Ding, Z., Oskarsson, M., Ardalan, A., Angleby, H., Dahlgren, L., Tepeli, C., Kirkness, E., Savolainen, P., & Zhang, Y. (2011) Origins of domestic dog in Southern East Asia is supported by analysis of Y-chromosome DNA. Heredity. DOI: 10.1038/hdy.2011.114
A new study involving bat skulls, bite force measurements and scat samples collected by an international team of evolutionary biologists is helping to solve a nagging question of evolution: Why some groups of animals develop scores of different species over time while others evolve only a few. Their findings appear in the current issue of Proceedings of the Royal Society B: Biological Sciences.
To answer this question, Elizabeth Dumont at the University of Massachusetts Amherst and Liliana D........ Read more »
Dumont, E., Davalos, L., Goldberg, A., Santana, S., Rex, K., & Voigt, C. (2011) Morphological innovation, diversification and invasion of a new adaptive zone. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2011.2005
One of the key questions in sexual selection theory is how do females choose the best mate? Research has generally focused on the role of male-male competition for access to receptive females, with less attention paid to female mate choice. Theory predicts that females should choose to mate with the most fit male available. In sexually dimorphic mammals, females may use body size as a surrogate for fitness, and choose to mate with the largest or most dominant males.
Alaskan moose (Alces ........ Read more »
Bowyer, R., Rachlow, J., Stewart, K., & Ballenberghe, V. (2011) Vocalizations by Alaskan moose: female incitation of male aggression. Behavioral Ecology and Sociobiology, 65(12), 2251-2260. DOI: 10.1007/s00265-011-1234-y
South America was isolated from Africa and the North American continent during most of the Cenozoic. As a result, early mammalian immigrants evolved in isolation resulting in a unique assemblage of terrestrial mammals. Approximately 34 million years ago (Eocene-Oligocene) global cooling and drying periods are believed to have spurred major faunal changes in South America terrestrial fauna,
including the arrival of caviomorph rodents.
One question that has long puzzled mammalogists is how........ Read more »
Antoine, P., Marivaux, L., Croft, D., Billet, G., Ganerod, M., Jaramillo, C., Martin, T., Orliac, M., Tejada, J., Altamirano, A.... (2011) Middle Eocene rodents from Peruvian Amazonia reveal the pattern and timing of caviomorph origins and biogeography. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2011.1732
Less than 3% of mammals are thought to be socially monogamous. However, with the advent of molecular techniques for establishing paternity, some presumably “monogamous” mammals may exhibit relatively high levels of extra pair paternity (EPP), or “cheating.”
Arctic fox (Vulpes lagopus, Figure 1) are a case in point. The arctic fox forage alone, but the social group usually consists of a breeding pair and their young (and occasionally a non-breeding female). Until j........ Read more »
Cameron, C., Berteaux, D., & Dufresne, F. (2011) Spatial variation in food availability predicts extrapair paternity in the arctic fox. Behavioral Ecology, 22(6), 1364-1373. DOI: 10.1093/beheco/arr158
Finding enough food to sustain the energy costs of foraging is a problem faced by all mammals. However, it is made more difficult for mammals that feed on unpredictable and limited prey. ... Molossus molossus (Figure 1), for example, is an aerial insectivore that forages in groups over large areas. Not only must they expend large amounts of energy to fuel these foraging flights, but they only forage for approximately one hour each night. How can they maintain a positive energy balance wit........ Read more »
Dechmann, D., Ehret, S., Gaub, A., Kranstauber, B., & Wikelski, M. (2011) Low metabolism in a tropical bat from lowland Panama measured using heart rate telemetry: an unexpected life in the slow lane. Journal of Experimental Biology, 214(21), 3605-3612. DOI: 10.1242/jeb.056010
Mammals are characterized by diphyodonty, only two generations of teeth, among other traits. However, a few mammals have evolved a form of continuous tooth replacement. For example, Manatees (Trichechus) add extra teeth at the back of the jaw as teeth near the front are worn away or lost. Such a conveyor-belt type of tooth replacement is exceedingly rare in mammals. The only other mammal know to exhibit continuous tooth replacement of this type is a metatherian, the pygmy-rock wallaby (P........ Read more »
Gomes Rodrigues, H., Marangoni, P., Sumbera, R., Tafforeau, P., Wendelen, W., & Viriot, L. (2011) Continuous dental replacement in a hyper-chisel tooth digging rodent. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1109615108
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