DOCSLIB.ORG

Factors Affecting the Evolution and Behavioral Ecology of the Modern Bears Author(S): Ian Stirling and Andrew E

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Factors Affecting the Evolution and Behavioral Ecology of the Modern Bears Author(S): Ian Stirling and Andrew E Factors Affecting the Evolution and Behavioral Ecology of the Modern Bears Author(s): Ian Stirling and Andrew E. Derocher Source: Bears: Their Biology and Management, Vol. 8, A Selection of Papers from the Eighth International Conference on Bear Research and Management, Victoria, British Columbia, Canada, February 1989 (1990), pp. 189-204 Published by: International Association of Bear Research and Management Stable URL: http://www.jstor.org/stable/3872919 Accessed: 03/01/2009 19:54 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=iba. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit organization founded in 1995 to build trusted digital archives for scholarship. We work with the scholarly community to preserve their work and the materials they rely upon, and to build a common research platform that promotes the discovery and use of these resources. For more information about JSTOR, please contact [email protected]. International Association of Bear Research and Management is collaborating with JSTOR to digitize, preserve and extend access to Bears: Their Biology and Management. http://www.jstor.org FACTORSAFFECTING THE EVOLUTION AND BEHAVIORAL ECOLOGY OF THE MODERNBEARS1 IAN STIRLING,Canadian Wildlife Service, 5320 122 St., Edmonton, Alberta, T6H 3S5, and Department of Zoology, University of Alberta, Edmonton, Alberta. T6G 2E9 ANDREW E. DEROCHER, Department of Zoology, University of Alberta, Edmonton, Alberta. T6G 2E9 Abstract: The present distribution and abundance of the ursids is but an ephemeral reflection of an evolutionary path that began with the first identifiable bear, the dawn bear (Ursavus elmensis), 20 million years ago in the early Miocene epoch. Although the dawn bear was only the size of a fox terrier, by the Pleistocene its descendents had evolved into some of the largest terrestrial carnivores the world has known. Most bear species evolved in the northern hemisphere although some dispersed and reached South America, Africa and SoutheastAsia. Each species had to cope with ecological changes that affected interspecific competition or the availability of food. Apparently the black bear was sufficiently adapted to have survived largely unchanged from what it was like a million years ago. Numerous species went extinct, leaving only the 8 still present today. Some understand- ing of the evolutionarypressures that the modem bearshave evolved throughmay help us to understandtheir behavioralecology. During the Pleistocene, bears at higher latitudes grew large and ecologically plastic while those closer to the equator remained small and became ecological specialists, as predicted by Geist's (1987) dispersal theory. Adaptations of the teeth of ancestral bear species allowed them to be both herbivores and carnivores. This allowed them to develop large size and broad ecological plasticity. Large body size enabled bears to conserve heat, capture large prey, defend carrion, travel great distances, and, as vegetation increased in the diet, to survive on qualitatively poorer food. Quantity and quality of available food and the degree of sexual dimorphism influenced the size of the home range and the evolution of social behaviorin each species. Bears show a great deal of individual variation in behavior and may exploit different subniches as a result of learned behavior. Slight differences in phenotype may also influence exploitation of subniches. Recent literature indicates that some terrestrial bear species are more active predators than previously thought and some evidence suggests a degree of scaling between the size of bears and the size of their prey. Social signalling appears to have been influenced by life in forest habitats but is not well understood. We give a preliminary interpretation of the social organization of the present day bears through the interactive framework of proximate ecological pressures, phylogenetichistory, and learning. There are likely few populations of bears anywhere in the world whose behavior has not been significantly influenced by man. This may confound our understanding of their behavior and ecology. Remaining populations of bears may not be able to adapt successfully to the combined effects of human predation, disappearing habitat, and climatic change. Int. Conf. Bear Res. and Manage. 8:189-204 The bears are a fascinating group to analyze in an and, in the northernhemisphere, the biomass and diver- evolutionarycontext because of the remarkablevariation sity of plants suitable for ungulates reached its zenith in their adaptations. The largest species are about 10 (Guthrie 1984). Savannas and steppes became wide- times heavier than the smallest. The degree of sexual spread. At higher latitudes and altitudes the climate dimorphismranges from species with none to those in amelioratedand vegetation became abundant during inter- which males are twice the size of females. Bears have glacial periods. Mammalgroups such as ungulatesdis- evolved specializedniches as carnivores,herbivores, and persed,speciated, and becamelarger (Geist 1978, 1987). myrmecophages,while retainingthe functionalability to During this period, the first identifiablebear species of be omnivores. Pandas,which normallyeat only 2 species the genus Ursus, U. minimus,appeared in the late Plio- of bamboo will still eat meat, while polar bears, which cene deposits of Europe. It probablygave rise to the specialize in hunting seals, also eat berries. The home present day members of the genus as well as several ranges of different species can range from less than 10 extinct species. km2to over 100,000 km2. Coincidentwith this largeincrease in the biomassand The present day distributionand abundanceof the diversity of prey species, there was an explosion in the ursids is but an ephemeralreflection of an evolutionary diversityof predators.From the late Pliocenethrough the path that began with the appearanceof the first identifi- Pleistocene,the bearsspeciated and evolved into some of able bear,the dawnbear, 20 million yearsago in the early the largest terrestrialcarivores known (Kurten 1968, Miocene epoch (Kurten 1976). Consequently,a brief Kurtenand Anderson1980). Duringthis period,several examinationof the evolutionaryhistory of moder bears species of bearsevolved, dispersed,and disappeared. An may help in interpretingthe available informationon importantpoint is that many more species once existed theirpresent day behavioralecology. The dawnbear was thando today. Forexample, severalspecies of the genus only about the size of a fox terrier,but even after 10 Tremarctoslived in southeasternNorth America (e.g., million years, its descendent Protursus, from the mid- the Floridacave bear,T.floridanus) and SouthAmerica. Miocene of Europe,was only modestly larger. Today only the spectacledbear (T. ornatus) survives in About 5 million years ago in the mid-Pliocene the the northernAndes. Similarly, the large short-faced worldclimate became drier (Kurten 1976, Guthrie1984) bears(Arctodus spp.) of NorthAmerica, the cave bearsof Eurasia Ursus in Invited paper (e.g., spelaeus Europe),various popula- 190 BEARS-THEIR BIOLOGY AND MANAGEMENT tions of brown bears (U. arctos) in Europe, Asia, and THE SIZE OF BEARS NorthAfrica, and the Langebaanwegbear (Agriotherium The modem bears are all medium- to large-sized africanum)of South Africa (Kurten 1966, 1967, 1968; mammals,ranging from 27 kg for the female Malayan Hendey 1977) all thrivedand subsequentlywent extinct. sun bear (U. malayanus)(Nowak and Paradiso1983) to In generalthough, the bearswere most successful where over 800 kg for an exceptionallylarge male polarbear in they originated,in northtemperate areas. primecondition (DeMaster and Stirling 1981). The latter Each species had to cope with a series of climatic representsa remarkableincrease in body size, relativeto changesthat in turnaffected interspecific competition or their small Miocene ancestor,the dawn bear,20 million alteredfood availability. A few, such as the American years ago. About 15 million years later, when Ursus black bear(U. americanus),were sufficientlyadapted to minimusfirst appeared,it weighed approximately50 kg, survive changingecological conditions and exist today, similarto the maximumweight of the male Malayansun largely unmodifiedfrom what they were like a million bear,the smallestof thepresent day ursids. Kurten(1976) yearsago. Thebrown bears and polar bears (U. maritimus) noted thatits canines were thin and sharpbut the molars of todayare morphologically similar to, thoughsmaller in had already become enlarged and better adapted for size, than their Pleistocene ancestors(Kurten 1976). feeding on vegetation, adaptationsthat together may An importantconsideration when analyzing the be- have madeit possible for the bearsto evolve a largebody. havioralecology of the presentday bears is the possible Even when the smallerspecies of bearsare
Load more

Recommended publications
  • Warm Weather Giants
    Warm Weather Giants New study delves into the relationship between climate and size in the Sabre-Tooth Cat Survival of the fittest. It is the underlying concept of natural selection, and the theory of evolution as a whole. The individuals best suited to their environment survive, procreate, and pass down their advantageous genes to future generations. Yet one factor that often is overlooked in this process is the dynamic nature of the environment. Climate change can cause dramatic shifts in an environment’s characteristics, completely changing the necessary skills and traits needed to survive. What was once an advantageous set of genes can quickly (in terms of an evolutionary time-scale) become a death sentence when they are present in an ill-suited setting. As we enter an era of dramatic and rapid warming of the planet, one can’t help but wonder how the world’s wildlife will change with their surroundings. When considering the future, it is often helpful to consult the past. Life on Earth is billions of years old, and has seen massive changes to the planet’s conditions. If we want to know more about how rapid climate change affects species, we must investigate the changes seen in prehistoric species in eras with an unsettled climate. “The Pleistocene period is really an ideal period to study,” says Dr. Julie Meachen from Des Moines University in Iowa. “It is recent enough that we have very good climate records with large swings in the conditions, and also have a well preserved fossil record from the tar pits.” Dr.
    [Show full text]
  • EXTRA-PAIR MATING and EFFECTIVE POPULATION SIZE in the SONG SPARROW (Melospiza Melodia)
    EXTRA-PAIR MATING AND EFFECTIVE POPULATION SIZE IN THE SONG SPARROW (Melospiza melodia) By Kathleen D. O'Connor B.A., Skidmore College, 2000 A THESIS SUBMITTED IN PARTIAL FUFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES THE FACULTY OF FORESTRY Department of Forest Sciences Centre for Applied Conservation Research We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA April 2003 © Kathleen D. O'Connor, 2003 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Fpce_t Sciences The University of British Columbia Vancouver, Canada Date 2HApc. 20O5 DE-6 (2/88) Abstract Effective population size is used widely in conservation research and management as an indicator of the genetic state of populations. However, estimates of effective population size for socially monogamous species can vary with the frequency of matings outside of the social pair. I investigated the effect of cryptic extra-pair fertilization on effective population size estimates using four years of demographic and genetic data from a resident population of song sparrows (Melospiza melodia Oberholser 1899) on Mandarte Island, British Columbia, Canada.
    [Show full text]
  • Shape Evolution and Sexual Dimorphism in the Mandible of the Dire Wolf, Canis Dirus, at Rancho La Brea Alexandria L
    Marshall University Marshall Digital Scholar Theses, Dissertations and Capstones 2014 Shape evolution and sexual dimorphism in the mandible of the dire wolf, Canis Dirus, at Rancho la Brea Alexandria L. Brannick [email protected] Follow this and additional works at: http://mds.marshall.edu/etd Part of the Animal Sciences Commons, and the Paleontology Commons Recommended Citation Brannick, Alexandria L., "Shape evolution and sexual dimorphism in the mandible of the dire wolf, Canis Dirus, at Rancho la Brea" (2014). Theses, Dissertations and Capstones. Paper 804. This Thesis is brought to you for free and open access by Marshall Digital Scholar. It has been accepted for inclusion in Theses, Dissertations and Capstones by an authorized administrator of Marshall Digital Scholar. For more information, please contact [email protected]. SHAPE EVOLUTION AND SEXUAL DIMORPHISM IN THE MANDIBLE OF THE DIRE WOLF, CANIS DIRUS, AT RANCHO LA BREA A thesis submitted to the Graduate College of Marshall University In partial fulfillment of the requirements for the degree of Master of Science in Biological Sciences by Alexandria L. Brannick Approved by Dr. F. Robin O’Keefe, Committee Chairperson Dr. Julie Meachen Dr. Paul Constantino Marshall University May 2014 ©2014 Alexandria L. Brannick ALL RIGHTS RESERVED ii ACKNOWLEDGEMENTS I thank my advisor, Dr. F. Robin O’Keefe, for all of his help with this project, the many scientific opportunities he has given me, and his guidance throughout my graduate education. I thank Dr. Julie Meachen for her help with collecting data from the Page Museum, her insight and advice, as well as her support. I learned so much from Dr.
    [Show full text]
  • Foraging : an Ecology Model of Consumer Behaviour?
    This is a repository copy of Foraging : an ecology model of consumer behaviour?. White Rose Research Online URL for this paper: https://eprints.whiterose.ac.uk/122432/ Version: Accepted Version Article: Wells, VK orcid.org/0000-0003-1253-7297 (2012) Foraging : an ecology model of consumer behaviour? Marketing Theory. pp. 117-136. ISSN 1741-301X https://doi.org/10.1177/1470593112441562 Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Foraging: an ecology model of consumer behavior? Victoria.K.Wells* Durham Business School, UK First Submission June 2010 Revision One December 2010 Revision Two August 2011 Accepted for Publication: September 2011 * Address for correspondence: Dr Victoria Wells (née James), Durham Business School, Durham University, Mill Hill Lane, Durham, DH1 3LB & Queen’s Campus, University Boulevard, Thornaby, Stockton-on-Tees, TS17 6BH, Telephone: +44 (0)191 334 0472, E-mail: [email protected] I would like to thank Tony Ellson for his guidance and Gordon Foxall for his helpful comments during the development and writing of this paper.
    [Show full text]
  • A NEW SABER-TOOTHED CAT from NEBRASKA Erwin H
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Conservation and Survey Division Natural Resources, School of 1915 A NEW SABER-TOOTHED CAT FROM NEBRASKA Erwin H. Barbour Nebraska Geological Survey Harold J. Cook Nebraska Geological Survey Follow this and additional works at: http://digitalcommons.unl.edu/conservationsurvey Part of the Geology Commons, Geomorphology Commons, Hydrology Commons, Paleontology Commons, Sedimentology Commons, Soil Science Commons, and the Stratigraphy Commons Barbour, Erwin H. and Cook, Harold J., "A NEW SABER-TOOTHED CAT FROM NEBRASKA" (1915). Conservation and Survey Division. 649. http://digitalcommons.unl.edu/conservationsurvey/649 This Article is brought to you for free and open access by the Natural Resources, School of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Conservation and Survey Division by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 36c NEBRASKA GEOLOGICAL SURVEY ERWIN HINCKLEY BARBOUR, State Geologist VOLUME 4 PART 17 A NEW SABER-TOOTHED CAT FROM NEBRASKA BY ERWIN H. BARBOUR AND HAROLD J. COOK GEOLOGICAL COLLECTIONS OF HON. CHARLES H. MORRILL 208 B A NEW SABER-TOOTHED CAT FROM NEBRASKA BY ERWIN H. BARBOUR AND HAROLD J, COOK During the field season of 1913, while exploring the Pliocene beds of Brown County, Mr. A. C. \Vhitford, a Fellow in the Department of Geology, University of Nebraska, discovered the mandible of a new mach.erodont cat. His work in this region was in the interest of the ~ebraska Geological Survey and the Morrill Geological Expeditions.1 The known fossil remains of the ancestral Felid.e fall into two nat­ ural lines of descent, as pointed out by Dr.
    [Show full text]
  • Mimicry - Ecology - Oxford Bibliographies 12/13/12 7:29 PM
    Mimicry - Ecology - Oxford Bibliographies 12/13/12 7:29 PM Mimicry David W. Kikuchi, David W. Pfennig Introduction Among nature’s most exquisite adaptations are examples in which natural selection has favored a species (the mimic) to resemble a second, often unrelated species (the model) because it confuses a third species (the receiver). For example, the individual members of a nontoxic species that happen to resemble a toxic species may dupe any predators by behaving as if they are also dangerous and should therefore be avoided. In this way, adaptive resemblances can evolve via natural selection. When this phenomenon—dubbed “mimicry”—was first outlined by Henry Walter Bates in the middle of the 19th century, its intuitive appeal was so great that Charles Darwin immediately seized upon it as one of the finest examples of evolution by means of natural selection. Even today, mimicry is often used as a prime example in textbooks and in the popular press as a superlative example of natural selection’s efficacy. Moreover, mimicry remains an active area of research, and studies of mimicry have helped illuminate such diverse topics as how novel, complex traits arise; how new species form; and how animals make complex decisions. General Overviews Since Henry Walter Bates first published his theories of mimicry in 1862 (see Bates 1862, cited under Historical Background), there have been periodic reviews of our knowledge in the subject area. Cott 1940 was mainly concerned with animal coloration. Subsequent reviews, such as Edmunds 1974 and Ruxton, et al. 2004, have focused on types of mimicry associated with defense from predators.
    [Show full text]
  • Person, J.J. 2012. Saber Teeth. Geo News 39(2)
    Saber Teeth Jeff J. Person Carnivores of all kinds have always been of interest to me. Arguably Smilodon is only the last iteration of saber-teeth in the fossil it is a much more difficult lifestyle to hunt and kill another animal record. Carnivorous mammals with large sabers have appeared than it is to browse or graze on non-mobile plants. Carnivorous four times across unrelated groups of carnivorous mammals over animals have evolved to stalk and kill their prey in many, many the last 60 million years (or so) of Earth’s history. varied ways. Just think of the speed of a frog’s tongue or the speed of a cheetah, the stealth and camouflage of an octopus, Types of Saber-teeth or the intelligence of some birds. These are only a few examples Not only were there four different groups of mammals that of modern carnivores; the variety of carnivores through time is evolved saber-teeth separately, there are also two different kinds broader and even more fascinating. of saber-teeth. There are the dirk-toothed forms, and the scimitar- toothed forms. The scimitar-toothed animals tended to be more Convergent evolution is the reappearance of the same solution lightly built with coarsely serrated and somewhat elongated to a biological problem across unrelated groups of animals. This canines (fig. 1) (Martin, 1998a). The dirk-toothed animals tended has happened many times throughout Earth’s history. The similar to be more powerfully built with long, finely serrated, dagger-like body shapes of sharks, fish, ichthyosaurs (a group of swimming canines which sometimes included a large flange on the lower jaw reptiles) and dolphins is a great example of unrelated groups of (fig.
    [Show full text]
  • Quaternary Records of the Dire Wolf, Canis Dirus, in North and South America
    Quaternary records of the dire wolf, Canis dirus, in North and South America ROBERT G. DUNDAS Dundas, R. G. 1999 (September): Quaternary records of the dire wolf, Canis dirus, in North and South Ameri- ca. Boreas, Vol. 28, pp. 375–385. Oslo. ISSN 0300-9483. The dire wolf was an important large, late Pleistocene predator in North and South America, well adapted to preying on megaherbivores. Geographically widespread, Canis dirus is reported from 136 localities in North America from Alberta, Canada, southward and from three localities in South America (Muaco, Venezuela; Ta- lara, Peru; and Tarija, Bolivia). The species lived in a variety of environments, from forested mountains to open grasslands and plains ranging in elevation from sea level to 2255 m (7400 feet). Canis dirus is assigned to the Rancholabrean land mammal age of North America and the Lujanian land mammal age of South Amer- ica and was among the many large carnivores and megaherbivores that became extinct in North and South America near the end of the Pleistocene Epoch. Robert G. Dundas, Department of Geology, California State University, Fresno, California 93740-8031, USA. E-mail: [email protected]; received 20th May 1998, accepted 23rd March 1999 Because of the large number of Canis dirus localities Rancho La Brea, comparing them with Canis lupus and and individuals recovered from the fossil record, the dire wolf specimens from other localities. Although dire wolf is the most commonly occurring large knowledge of the animal’s biology had greatly predator in the Pleistocene of North America. By increased by 1912, little was known about its strati- contrast, the species is rare in South America.
    [Show full text]
  • Shell Resource Partitioning As a Mechanism of Coexistence in Two Co‑Occurring Terrestrial Hermit Crab Species Sebastian Steibl and Christian Laforsch*
    Steibl and Laforsch BMC Ecol (2020) 20:1 https://doi.org/10.1186/s12898-019-0268-2 BMC Ecology RESEARCH ARTICLE Open Access Shell resource partitioning as a mechanism of coexistence in two co-occurring terrestrial hermit crab species Sebastian Steibl and Christian Laforsch* Abstract Background: Coexistence is enabled by ecological diferentiation of the co-occurring species. One possible mecha- nism thereby is resource partitioning, where each species utilizes a distinct subset of the most limited resource. This resource partitioning is difcult to investigate using empirical research in nature, as only few species are primarily limited by solely one resource, rather than a combination of multiple factors. One exception are the shell-dwelling hermit crabs, which are known to be limited under natural conditions and in suitable habitats primarily by the avail- ability of gastropod shells. In the present study, we used two co-occurring terrestrial hermit crab species, Coenobita rugosus and C. perlatus, to investigate how resource partitioning is realized in nature and whether it could be a driver of coexistence. Results: Field sampling of eleven separated hermit crab populations showed that the two co-occurring hermit crab species inhabit the same beach habitat but utilize a distinct subset of the shell resource. Preference experiments and principal component analysis of the shell morphometric data thereby revealed that the observed utilization patterns arise out of diferent intrinsic preferences towards two distinct shell shapes. While C. rugosus displayed a preference towards a short and globose shell morphology, C. perlatus showed preferences towards an elongated shell morphol- ogy with narrow aperture. Conclusion: The two terrestrial hermit crab species occur in the same habitat but have evolved diferent preferences towards distinct subsets of the limiting shell resource.
    [Show full text]
  • Social Relations Chapter 8 Behavioral Ecology
    Social Relations Chapter 8 Behavioral Ecology: Study of social relations. Studies interactions between organisms and the environment mediated by behavior 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Some differences between males and females…besides the obvious!!! • Females produce larger, more energetically costly gametes. • Males produce smaller, less energetically costly gametes. Female reproduction thought to be limited by resource access. Male reproduction limited by mate access. http://www.youtube.com/watch?v =NjnFBGW3Fmg&feature=related2 Hermaphrodites • Hermaphrodites Exhibit both male and female function. Most familiar example is plants. So, how do organisms choose their mate??? 3 Mate Choice • Sexual Selection Differences in reproductive rates among individuals as a result of differences in mating success. Intrasexual Selection: Individuals of one sex compete among themselves for mates. Intersexual Selection: Individuals of one sex consistently choose mates among members of opposite sex based on a particular trait. http://www.youtube.co m/watch? v=eYU4v_ZTRII 4 How much is too much??? • Darwin proposed that sexual selection would continue until balanced by other sources of natural selection • Given a choice, female guppies will mate with brightly colored males. However, brightly colored males attract predators. It’s a trade-off! 5 Class Activity!!! • In groups, using guys in a bar looking for dates example, come up with a scenario of sexual selection either going too far or succeeding!!! Be creative!!! 6 Sexual Selection in Plants??? Nonrandom Mating Found Among Wild Radish • Wild radish flowers have both male (stamens) and female (pistils) parts, but cannot self-pollinate. • Marshall found non-random mating in wild radish populations.
    [Show full text]
  • Large Pleistocene Felines of North America by George Gaylord Simpson
    AMERICAN MUSEUM NOVITATES Published by Number 1136 THE AMERICAN MUSEUM OF NATURAL HISTORY August 11, 1941 New York City LARGE PLEISTOCENE FELINES OF NORTH AMERICA BY GEORGE GAYLORD SIMPSON About thirty occurrences of true cats, ends can be gathered, but on present evi- felines, of the size of pumas or larger have dence it seems possible to establish the been reported in the Pleistocene of North following conclusions: America. Except for the specimens from 1.-Known large Pleistocene felines from the asphalt of Rancho La Brea and of Mc- North America suffice to demonstrate the pres- Kittrick, in California, these are neverthe- ence of three, and only three, groups: pumas, less relatively rare fossils and the specimens jaguars, and P. atrox. 2.-Although scattered from the Atlantic to are usually fragmentary. They have been the Pacific Coasts, the Pleistocene pumas do assigned by various students to about not, in the known parts, show much if any more fifteen different species and their affinities variation than do recent pumas of one subspecies and taxonomy have not been understood. and of more limited geographic distribution. They average a little larger than recent pumas Many have been placed in extinct, or sup- and show minor morphologic distinction of not posedly extinct, species with no definite more than specific value and possibly less. idea as to their relationships to other cats. The definitions of the several supposedly dis- A few have been recognized as pumas, or as tinct groups are not yet satisfactory. 3.-True jaguars specifically inseparable from related to pumas, but on the other hand Panthera onca, the living species, occur widely.
    [Show full text]
  • Where Is Behavioural Ecology Going?
    Opinion TRENDS in Ecology and Evolution Vol.21 No.7 July 2006 Where is behavioural ecology going? Ian P.F. Owens Division of Biology and NERC Centre for Population Biology, Imperial College London, Silwood Park, Ascot, Berkshire, UK, SL5 7PY Since the 1990s, behavioural ecologists have largely wove together the theories developed over the preceding abandoned some traditional areas of interest, such as decade and championed a new empirical approach to optimal foraging, but many long-standing challenges investigating behaviour. The key element of this approach remain. Moreover, the core strengths of behavioural was the use of adaptation as the central conceptual ecology, including the use of simple adaptive models to framework, which gave behavioural ecologists a precise investigate complex biological phenomena, have now a priori expectation: behaviours should evolve to maxi- been applied to new puzzles outside behaviour. But this mise the fitness of the individuals showing strategy comes at a cost. Replication across studies is those behaviours. rare and there have been few tests of the underlying Krebs and Davies also stressed the importance of two genetic assumptions of adaptive models. Here, I attempt other principles [27]. The first was the need to quantify to identify the key outstanding questions in behavioural variation in behaviour accurately. Drawing attention to ecology and suggest that researchers must make the new quantitative work that was being performed in greater use of model organisms and evolutionary some areas of ethology [28,29], they showed how this genetics in order to make substantial progress on approach could be applied to a variety of behaviours.
    [Show full text]