青藏高原有蹄类动物多样性和特有性: 演化与保护

青藏高原是地球上一个独特的自然地理单元, 具有丰富的生境类型和生物种类, 是生物多样性与全球环境变化领域的热点研究区域。青藏高原发育着独特的动物区系, 尤其是有蹄类动物, 如藏羚(Pantholops hodgsonii)、野牦牛(Bos mutus)、藏原羚(Procapra picticaudata)、普氏原羚(P. przewalskii)、白唇鹿(Przewalskium albirostris)等青藏高原特有动物。在本文中, 我们探讨了如下问题: 青藏高原有多少种有蹄类动物?有多少种特有有蹄类动物?其分布格局如何?生存状况如何?保护现状如何?我们首先确定了青藏高原动物地理区的地理边界。发现青藏高原有28种有蹄类, 其中10种是青藏高原特有种。青藏高原有蹄类种数占中国有蹄类的42%, 单位面积上的有蹄类物种密度比中国现生有蹄类物种平均密度高62%。特有种比例高达36%。然而, 青藏高原有蹄类物种分布不均匀, 其丰富度呈东部高西部低格局, 而高原特有有蹄类则分布于高原腹地。青藏高原有蹄类动物生存受威胁比例高, 其中71%为受威胁物种, 54%被列入濒危野生动植物种国际贸易公约(CITES)附录I或附录II。野外调查发现大额牛(Bos frontalis)已经野外灭绝, 目前仅在高黎贡山有人工养殖的群体。青藏高原有蹄类物种红色名录指数从1998-2015年呈现持续下降趋势, 全球气候变化将加剧这一趋势。青藏高原有蹄类受威胁局面仍在继续, 物种生存状况持续恶化。虽然经过40年的自然保护区建设, 但一些青藏高原有蹄类的重要种群与栖息地并没有被自然保护区和新建的三江源国家公园所覆盖。因此, 在开发青藏高原、实现人类社会经济发展目标的同时, 应尽量保存高原野生动物种群与生境, 实现青藏高原草地生态系统的可持续利用与生物多样性保护的双赢目标。     

On the relationship between hypsodonty and feeding ecology in ungulate mammals,and its utility in palaeoecology

High‐crowned (hypsodont) teeth are widely found among both extant and extinct mammalian herbivores. Extant grazing ungulates (hoofed mammals) have hypsodont teeth (a derived condition), and so extinct hypsodont forms have usually been presumed to have been grazers. Thus, hypsodonty among ungulates has, over the past 150 years, formed the basis of widespread palaeoecological interpretations, and has figured prominently in the evolutionary study of the spread of grasslands in the mid Cenozoic. However, perceived inconsistencies between levels of hypsodonty and dental wear patterns in both extant and extinct ungulates have caused some workers to reject hypsodonty as a useful predictive tool in palaeobiology, a view that we consider both misguided and premature. Despite the acknowledged association between grazing and hypsodonty, the quantitative relationship of hypsodonty to the known ecology of living ungulate species, critical in making interpretations of the fossil record, was little studied until the past two decades. Also, much of the literature on ungulate ecology relevant to understanding hypsodonty has yet to be fully incorporated into the perspectives of palaeontologists. Here we review the history and current state of our knowledge of the relationship between hypsodonty and ungulate ecology, and reassert the value of hypsodonty for our understanding of ungulate feeding behaviour. We also show how soil consumption, rather than the consumption of grass plants per se, may be the missing piece of the puzzle in understanding the observed correlation between diets, habitats, and hypsodonty in ungulates. Additionally, we show how hypsodonty may impact life‐history strategies, and resolve some controversies regarding the relevance of hypsodonty to the prediction of the diets of extinct species. This in turn strengthens the utility of hypsodonty in the determination of past environmental conditions, and we provide a revised view of a traditional example of evolutionary trends in palaeobiology, that of the evolution of hypsodonty in horses and its correlation with the Miocene spread of grasslands in North America.     

Conversion of native terrestrial ecosystems in Hawai‘i to novel grazing systems: a review

The remote oceanic islands of Hawai‘i exemplify the transformative effects that non-native herbivorous mammals can bring to isolated terrestrial ecosystems. We reviewed published literature containing systematically collected, analyzed, and peer-reviewed original data specifically addressing direct effects of non-native hoofed mammals (ungulates) on terrestrial ecosystems, and indirect effects and interactions on ecosystem processes in Hawai‘i. The effects of ungulates on native vegetation and ecosystems were addressed in 58 original studies and mostly showed strong short-term regeneration of dominant native trees and understory ferns after ungulate removal, but unassisted recovery was dependent on the extent of previous degradation. Ungulates were associated with herbivory, bark-stripping, disturbance by hoof action, soil erosion, enhanced nutrient cycling from the interaction of herbivory and grasses, and increased pyrogenicity and competition between native plants and pasture grasses. No studies demonstrated that ungulates benefitted native ecosystems except in short-term fire-risk reduction. However, non-native plants became problematic and continued to proliferate after release from herbivory, including at least 11 species of non-native pasture grasses that had become established prior to ungulate removal. Competition from non-native grasses inhibited native species regeneration where degradation was extensive. These processes have created novel grazing systems which, in some cases, have irreversibly altered Hawaii’s terrestrial ecology. Non-native plant control and outplanting of rarer native species will be necessary for recovery where degradation has been extensive. Lack of unassisted recovery in some locations should not be construed as a reason to not attempt restoration of other ecosystems.     

Muscles of the masticatory apparatus in two genera of hyraces (Procavia and Heterohyrax)

Subungulate hyraces are similar to the condition assumed to have characterized primitive ungulates and subungulates by virtue of their small body size, relatively unspecialized cranial and postcranial anatomy, and primitive type of lophodont dentition. The muscles of mastication of Procavia habessinica and Heterohyrax brucei are here compared with those of other mammals, both with ungulates, as an example of more specialized mammals, and with opossums, as an example of more generalized mammals, to determine aspects of hyrax myology that represent the retention of a condition primitive for herbivorous mammals. The masticatory muscles of hyraces retain the primitive ungulate/subungulate condition in the large, complexly subdivided temporalis, and in the enlarged, pinnated, bilayered medial pterygoid. The medial pterygoid originates from the pterygoid hamulus, a condition that may also be primitive for this assemblage. The large complex superficial masseter is derived compared with the condition in ruminant artiodactyls, but may represent the condition primitive for perissodactyls. The architectural modifications of this muscle in hyraces may represent adaptations to allow a wide gape threat display. Hyraces possess a posterior belly of the digastric alone, paralleling the condition in some perissodactyls. They possess a large and complexly subdivided styloglossus, which may be a shared derived character of subungulates. Hyraces are unique among ungulates and subungulates in the extreme reduction of the anterior hyoid cornua, and may be unique among mammals in the development of paired lingual processes from the ceratohyal ossifications.     

<Emphasis Type="Italic">Protungulatum</Emphasis>, Confirmed Cretaceous Occurrence of an Otherwise Paleocene Eutherian (Placental?) Mammal

Neither pre-Cenozoic crown eutherian mammals (placentals) nor archaic ungulates (“condylarths”) are known with certainty based on the fossil record. Herein we report a new species of the Paleocene archaic ungulate (“condylarth”) Protungulatum from undisputed Late Cretaceous aged rocks in Montana USA based on an isolated last upper premolar, indicating rare representatives of these common early Tertiary mammals appeared in North America a minimum of 300 k  years before the extinction of non-avian dinosaurs. The other 1200 mammal specimens from the locality are characteristic Late Cretaceous taxa. This discovery overturns the current hypothesis that archaic ungulates did not appear in North America until after the Cretaceous/Tertiary (K/T) boundary and also suggests that other reports of North American Late Cretaceous archaic ungulates may be correct. Recent studies, including ours, cannot determine whether Protungulatum does or does not belong to the crown clade Placentalia.     

Diet,Prey Selection,and Predation Impact of Black-Backed Jackals in South Africa

ABSTRACT To investigate the role of black-backed jackals (Canis mesomelas) as predators, we studied diet, prey selection, and predation impact of jackals on 2 game ranches in South Africa that differed in ungulate diversity and biomass. Results showed that large (>15 kg) ungulate species dominated jackal diets throughout the year on both the less diverse (range of ingested biomass across seasons = 39–78%) and more diverse (26–69%) game ranch. Other important food items included medium-sized mammals (1–3 kg; 1–26%) and fruit (2–69%), whereas small mammals comprised 3–11% of ingested biomass across seasons on both sites. Jackals were not random in consumption of ungulates, and consumption patterns suggested jackals actively hunted certain species rather than consumed them as carrion. During ungulate birthing periods, jackals consumed almost exclusively those ungulate species that were hiders (i.e., fawns were hidden in tall vegetation away from herd) regardless of ungulate densities, suggesting that primarily fawns were preyed upon. Among hiders, there was a negative relationship (P = 0.01) between body size and percent of population consumed by jackals, indicating smaller species were more susceptible than larger species to jackal predation. Consequently, springbok (Antidorcas marsupialis) were always selected over other ungulate species on both sites, and this species was the most impacted by jackal predation. In contrast, ungulate species that were followers (i.e., fawns immediately followed mothers within protection of the herd) were scarcely or not at all consumed by jackals, regardless of body size or density. Medium-sized mammals were selectively consumed over ungulates, and there was a negative relationship (P < 0.01) between consumption of berries and ungulates, indicating alternative food resources influenced consumption of ungulates on our study sites. Our results will help wildlife managers in Africa identify ungulate species susceptible to jackal predation, and can be used to develop management strategies for reducing jackal predation in areas where it is problematic.     

Ungulates,rodents, shrubs: interactions in a diverse Mediterranean ecosystem

Ungulate abundance has increased dramatically worldwide, having strong impacts on ecosystem functioning. High ungulate densities can reduce the abundance, diversity and/or body condition of small mammals, which has been attributed to reductions in cover shelter and food availability by ungulates. The densities of wild ungulates have increased recently in high-diversity Mediterranean oak ecosystems, where acorn-dispersing small rodents are keystone species. We analysed experimentally ungulate effects on seed-dispersing rodents in two types of oak woodland: a forest with dense shrub layer and in dehesas lacking shrubs. Ungulates had no significant effects on vegetation structure or rodent body mass, but they reduced dramatically rodent abundance in the lacking-shrub dehesas. In the forest, ungulates modified the spatial distribution and space use of rodents, which were more concentrated under shrubs in the presence than in the absence of ungulates. Our results point to the importance of shrubs in mediating ungulate–rodent interactions in Mediterranean areas, suggesting that shrubs serve as shelter for rodents against ungulate physical disturbances such as soil compaction, trampling or rooting. Holm oak seedling density was reduced by ungulates in dehesa plots, but not in forests. Acorn consumption by ungulates may reduce oak recruitment to a great extent. Additionally, we suggest that ungulates may have a negative effect on oak regeneration processes by reducing the abundance of acorn-dispersing rodents. Given that shrubs seem to mediate ungulate effects on acorn dispersers, controlled shrub encroachment could be an effective alternative to ungulate population control or ungulate exclusion for the sustainability of the high-diversity Mediterranean oak ecosystems.     

Comparative phylogeography of African savannah ungulates

The savannah biome of sub-Saharan Africa harbours the highest diversity of ungulates (hoofed mammals) on Earth. In this review, we compile population genetic data from 19 codistributed ungulate taxa of the savannah biome and find striking concordance in the phylogeographic structuring of species. Data from across taxa reveal distinct regional lineages, which reflect the survival and divergence of populations in isolated savannah refugia during the climatic oscillations of the Pleistocene. Data from taxa across trophic levels suggest distinct savannah refugia were present in West, East, Southern and South-West Africa. Furthermore, differing Pleistocene evolutionary biogeographic scenarios are proposed for East and Southern Africa, supported by palaeoclimatic data and the fossil record. Environmental instability in East Africa facilitated several spatial and temporal refugia and is reflected in the high inter- and intraspecific diversity of the region. In contrast, phylogeographic data suggest a stable, long-standing savannah refuge in the south.     

The feeding habits of wolves in relation to large prey availability in northern Italy

We investigated wolf feeding habits in relation to the abundance of wild and domestic ungulates to test the hypothesis that large prey are preferred and that their abundance affects the use of other food categories and diet breadth. We determined diet composition by scat analysis from December 1987 to December 1992. The research was carried out in three study areas located in northern Italy and characterised by marked differences in wild and domestic ungulate abundance. In study area A (low wild and domestic ungulate availability) fruits, livestock, other vertebrates and wild ungulates made up the bulk of the diet (71% in volume). In area B (high availability of livestock) wolf diet was mainly based on sheep and wild boars (80% in volume). In study area C (high availability of wild ungulates) wild ungulates were the main food of wolves (90% in volume). Significant differences were found among study areas in the mean percentage volume of all food categories and in particular for wild ungulates, livestock, other vertebrates and fruits (p < 0.0001 in all cases). Diet breadth decreased in areas with high availability of large wild and domestic herbivores. The use of livestock species was lower where there was high abundance, richness and diversity of the wild ungulate guild. Selection for wild ungulate species was partially affected by their abundance: however other factors as prey social behaviour, adaptability to the habitat (for introduced species), and body size could have an important role in species selection by wolves. In particular in area C wild boars were selected for, roe and red deers avoided, and fallow deers and mouflons used as available. Livestock species were used in relation to their abundance and accessibility, in particular sheep were selected for and cattle avoided; but if calves bom in the pastures were considered as the only available cattle, they were selected for and sheep were used as available. Large and in particular wild herbivores were found to be of great importance for the wolf population maintenance in northern Italy, one of the most important recovery areas of Mediterranean wolves.     

Progressively excluding mammals of different body size affects community and trait structure of ground beetles

Mammalian grazing induces changes in vegetation properties in grasslands, which can affect a wide variety of other animals including many arthropods. However, the impacts may depend on the type and body size of these mammals. Furthermore, how mammals influence functional trait syndromes of arthropod communities is not well known. We progressively excluded large (e.g. red deer, chamois), medium (e.g. alpine marmot, mountain hare), and small (e.g. mice) mammals using size‐selective fences in two vegetation types (short‐ and tall‐grass vegetation) of subalpine grasslands. We then assessed how these exclusions affected the community composition and functional traits of ground beetles (Coleoptera, Carabidae), and which vegetation characteristic mediated the observed effects. Total carabid biomass, the activity densities of carabids with specific traits (i.e. small eyes, short wings), the richness of small‐eyed species and the richness of herbivorous species were significantly higher when certain mammals were excluded compared to when all mammals had access, regardless of vegetation type. Excluding large and medium mammals increased the activity density of herbivorous carabid species, but only in short‐grass vegetation. Similarly, excluding large mammals (ungulates) altered carabid species composition in the short‐, but not in the tall‐grass vegetation. All these responses were related to aboveground plant biomass, but not to plant Shannon diversity or vegetation structural heterogeneity. Our results indicate that changes in aboveground plant biomass are key drivers of mammalian grazers’ influence on carabids, suggesting that bottom–up forces are important in subalpine grassland systems. The exclusion of ungulates provoked the strongest carabid response. Our results, however, also highlight the ecological significance of smaller herbivorous mammals. Our study furthermore shows that mammalian grazing not only altered carabid community composition, but also caused community‐wide functional trait shifts, which could potentially have a wider impact on species interactions and ecosystem functioning.     

MUTUALISM OR PARASITISM? USING A PHYLOGENETIC APPROACH TO CHARACTERIZE THE OXPECKER‐UNGULATE RELATIONSHIP

With their striking predilection for perching on African ungulates and eating their ticks, yellow-billed (Buphagus africanus) and red-billed oxpeckers (B. erythrorhynchus) represent one of the few potentially mutualistic relationships among vertebrates. The nature of the oxpecker-ungulate relationship remains uncertain, however, because oxpeckers are known to consume ungulate tissues, suggesting that the relationship between oxpeckers and ungulates may also be parasitic. To examine this issue further, we obtained data on oxpecker preferences for different ungulate species, the abundance of ticks on these ungulates, and ungulate hide thickness. In support of the mutualism hypothesis, we found that both species of oxpeckers prefer ungulate hosts that harbor a higher abundance of ticks. We found no evidence that hide thickness-a measure of the potential for parasitism by oxpeckers-predicts oxpecker preferences for different ungulate species. Oxpeckers also prefer larger-bodied ungulates, possibly because larger animals have more ticks, provide a more stable platform upon which to forage, or support more oxpeckers feeding simultaneously. However, the preference for ungulates with greater tick abundance was independent of host body mass. These results support the hypothesis that the relationship between oxpeckers and ungulates is primarily mutualistic.     

佛坪自然保护区6种有蹄动物的活动痕迹监测

野生动物监测在保护管理自然资源以确保可持续利用上占有关键地位.然而,我国对大型哺乳动物的长期监测基本尚未纳入常规.佛坪自然保护区自20世纪90年代中期就大熊猫等珍稀动物及其栖息环境展开了长期监测.以该保护区2000～2006年监测数据为基础,探讨了该地有蹄类动物(除扭角羚外)的资源动态及在生境因子利用上的差异.结果表明该保护区内有蹄类动物资源在不同区域的分布并不均衡,以三官庙区域的痕迹密度最高而以龙潭区域为最低.监测期间有蹄类动物资源呈现出逐步下降的趋势.物种两两之间在海拔、坡度等生境因子的利用上大多存在显著差异,表现出不同的微生境利用模式.最后就监测对象的确定以及监测方法的选择进行了探讨,该保护区所采用的监测方法较为科学有效.     

Evolution of the cytochromeb gene of mammals

Summary With the polymerase chain reaction (PCR) and versatile primers that amplify the whole cytochromeb gene (∼ 1140 bp), we obtained 17 complete gene sequences representing three orders of hoofed mammals (ungulates) and dolphins (cetaceans). The fossil record of some ungulate lineages allowed estimation of the evolutionary rates for various components of the cytochromeb DNA and amino acid sequences. The relative rates of substitution at first, second, and third positions within codons are in the ratio 10 to 1 to at least 33. For deep divergences (>5 million years) it appears that both replacements and silent transversions in this mitochondrial gene can be used for phylogenetic inference. Phylogenetic findings include the association of (1) cetaceans, artiodactyls, and perissodactyls to the exclusion of elephants and humans, (2) pronghorn and fallow deer to the exclusion of bovids (i. e., cow, sheep, and goat), (3) sheep and goat to the exclusion of other pecorans (i. e., cow, giraffe, deer, and pronghorn), and (4) advanced ruminants to the exclusion of the chevrotain and other artiodactyls. Comparisons of these cytochromeb sequences support current structure-function models for this membrane-spanning protein. That part of the outer surface which includes the Q_o redox center is more constrained than the remainder of the molecule, namely, the transmembrane segments and the surface that protrudes into the mitochondrial matrix. Many of the amino acid replacements within the transmembrane segments are exchanges between hydrophobic residues (especially leucine, isoleucine, and valine). Replacement changes at first and second positions of codons approximate a negative binomial distribution, similar to other protein-coding sequences. At four-fold degenerate positions of codons, the nucleotide substitutions approximate a Poisson distribution, implying that the underlying mutational spectrum is random with respect to position.     

Oscillations in large mammal populations: are they related to predation or rainfall?

Cyclic population dynamics is relatively common among populations of small mammals in high latitudes but is not yet established among African savanna ungulates. However, oscillations may be expected in large mammal populations subject to quasi‐periodic oscillations in regional rainfall. We evaluated evidence for environmentally entrained oscillations in a large‐mammal predator–prey system in Kruger National Park (KNP), South Africa, where rainfall exhibits quasi‐periodic oscillations. The evaluation is based on analysis of comparative changes in the abundance of twelve ungulate species throughout South Africa's KNP using population counts over the period 1965–1996. We present evidence suggesting that (i) twelve ungulate populations display cyclic variability with half‐periods ranging between 10 and 18 years, (ii) this variability was associated with lagged rainfall between 3 and 10 years back in the past for different ungulate species, and (iii) the ungulate species respond in contrasting ways to rainfall, with some reaching highest abundance during periods of low rainfall and others under conditions of high rainfall. These findings are not consistent with the response pattern we would expect if the population oscillations were driven directly by the rainfall influence on food availability. Instead they seem to be an outcome of predator–prey interactions, which are entrained by the effect of rainfall on habitat conditions affecting the relative susceptibility of the different ungulate species to predation.     

Digital cranial endocast of Hyopsodus (Mammalia, "Condylarthra"): a case of paleogene terrestrial echolocation?

We here describe the endocranial cast of the Eocene archaic ungulate Hyopsodus lepidus AMNH 143783 (Bridgerian, North America) reconstructed from X-ray computed microtomography data. This represents the first complete cranial endocast known for Hyopsodontinae. The Hyopsodus endocast is compared to other known "condylarthran" endocasts, i. e. those of Pleuraspidotherium (Pleuraspidotheriidae), Arctocyon (Arctocyonidae), Meniscotherium (Meniscotheriidae), Phenacodus (Phenacodontidae), as well as to basal perissodactyls (Hyracotherium) and artiodactyls (Cebochoerus, Homacodon). Hyopsodus presents one of the highest encephalization quotients of archaic ungulates and shows an "advanced version" of the basal ungulate brain pattern, with a mosaic of archaic characters such as large olfactory bulbs, weak ventral expansion of the neopallium, and absence of neopallium fissuration, as well as more specialized ones such as the relative reduction of the cerebellum compared to cerebrum or the enlargement of the inferior colliculus. As in other archaic ungulates, Hyopsodus midbrain exposure is important, but it exhibits a dorsally protruding largely developed inferior colliculus, a feature unique among "Condylarthra". A potential correlation between the development of the inferior colliculus in Hyopsodus and the use of terrestrial echolocation as observed in extant tenrecs and shrews is discussed. The detailed analysis of the overall morphology of the postcranial skeleton of Hyopsodus indicates a nimble, fast moving animal that likely lived in burrows. This would be compatible with terrestrial echolocation used by the animal to investigate subterranean habitat and/or to minimize predation during nocturnal exploration of the environment.     

Early Tertiary mammals from North Africa reinforce the molecular Afrotheria clade

The phylogenetic pattern and timing of the radiation of mammals, especially the geographical origins of major crown clades, are areas of controversy among molecular biologists, morphologists and palaeontologists. Molecular phylogeneticists have identified an Afrotheria clade, which includes several taxa as different as tenrecs (Tenrecidae), golden moles (Chrysochloridae), elephant-shrews (Macroscelididae), aardvarks (Tubulidentata) and paenungulates (elephants, sea cows and hyracoids). Molecular data also suggest a Cretaceous African origin for Afrotheria within Placentalia followed by a long period of endemic evolution on the Afro-Arabian continent after the mid-Cretaceous Gondwanan breakup (approx. 105-25 Myr ago). However, there was no morphological support for such a natural grouping so far. Here, we report new dental and postcranial evidence of Eocene stem hyrax and macroscelidid from North Africa that, for the first time, provides a congruent phylogenetic view with the molecular Afrotheria clade. These new fossils imply, however, substantial changes regarding the historical biogeography of afrotheres. Their long period of isolation in Africa, as assumed by molecular inferences, is now to be reconsidered inasmuch as Eocene paenungulates and elephant-shrews are here found to be related to some Early Tertiary Euramerican 'hyopsodontid condylarths' (archaic hoofed mammals). As a result, stem members of afrotherian clades are not strictly African but also include some Early Paleogene Holarctic mammals.     

Euroceros bulgaricus gen. nov., sp. nov. from Hadzhidimovo (SW Bulgaria) (Late Miocene) - the first European record of Hornbills (Aves: Coraciiformes)

A new genus and species of ground-hornbill are described from the Late Tertiary (Late Miocene) fluviative deposits in Hadzhidimovo (Hadzhidimovo-1, or Hadzhidimovo-Girizite locality), in southwestern Bulgaria. The cranial half of a scapula and the distal third of a femur have been recovered. The morphology distinguishes the specimen from the recent species of Bucorvus, the closest genus. Most interesting is the morphology of the scapula (the holotype), which differs considerably from the ground-hornbills in some structures (e.g. the clavicular joint) while being surprisingly similar in other structures (e.g. the humeral articular joint). The last peculiarity may indicate that the fossil species was a more primitive form having relatively poorer flying capacity in comparison to other ground-hornbills. This first record of Bucerotidae in Europe proves the occurrence of the family in the Tertiary of the western parts of the Eurasian continent. It came from the richest Bulgarian locality of the Hipparion fauna, from which ca. 36 species of large mammals and birds are now known.     

Comparative molecular cytogenetics in cetartiodactyla

Cetartiodactyla comprises Artiodactyla (even-toed ungulates) and Cetacea (whales, dolphins and porpoises). Artiodactyla is a large taxon represented by about 200 living species ranked in 10 families. Cetacea are classified into 13 families with almost 80 species. Many publications concerning karyotypic relationships in Cetartiodactyla have been published in previous decades. Formerly, the karyotypes of closely related species were compared by chromosome banding. Introduction of molecular cytogenetic methods facilitated comparative mapping between species with highly rearranged karyotypes and distantly related species. Such information is a prerequisite for the understanding of karyotypic phylogeny and the reconstruction of the karyotypes of common ancestors. This study summarizes the data on chromosome evolution in Cetartiodactyla, mainly derived from molecular cytogenetic studies. Traditionally, phylogenetic relationships of most groups have been estimated using morphological data. However, the results of some molecular studies of mammalian phylogeny are discordant with traditional conceptions of phylogeny. Cetartiodactyls provide several examples of incongruence between traditional morphological and molecular data. Such cases of conflict include the relationships of the major clades of artiodactyls, the relationships among the extant families of the suborder Ruminantia or the phylogeny of the family Bovidae. The most unexpected aspect of the molecular phylogeny was the recognition that Cetacea is a deeply nested member of Artiodactyla. The largest living order of terrestrial hoofed mammals is the even-toed hoofed mammals, or Artiodactyla. The artiodactyls are composed of over 190 living species including pigs, peccaries, hippos, camels, llamas, deer, pronghorns, giraffes, sheep, goats, cattle and antelopes. Cetacea is an order of wholly aquatic mammals, which include whales, dolphins and porpoises. Cetartiodactyla has become the generally accepted name for the clade containing both of these orders.     

Were there mammalian pursuit predators in the tertiary? Dances with wolf avatars

Fast-running, long-legged pursuit carnivores are familiar members of the present-day ecosystem, and it has been assumed that extinct large predators took similar ecomorphological roles (i.e., were wolf avatars) in past faunas. While these fossil taxa may also have been meat-specialists, we present evidence from limb morphology to show that there was no modern type of pursuit predator until the latest Tertiary. In contrast, ungulates evolved longer legs similar to those of present-day cursorial taxa by the middle Tertiary, some 20 million years earlier. These data suggest the need for the reevaluation of many classical evolutionary stories, not only about assignation of fossil taxa to a wolf-like mode of predatory behavior, but also to issues such as the coevolution of long legs and fast running speeds between predator and prey, and even the implicit assumption that cursorial morphologies are primarily an adaptation for speed. We conclude that evolutionary change in ungulate limb morphologies represents an adaptation to decrease transport costs in association with Tertiary climatic changes and that the present-day predation mode of long distance pursuit is a Plio-Pleistocene phenomenon, related to the development of colder and more arid climates.     

Regulation, cycles and stability in northern carnivore-herbivore systems: back to first principles

In studies on dynamics of northern predator‐prey systems, two assumptions are often made. First, the bifurcation from stable to cyclic dynamics is seen as a consequence of changing generalist‐specialist ratio, ultimately due to reduced prey diversity at high latitudes and the negative impact of snow on the efficiency of generalists as predators of small, folivorous mammals. Supposedly, the primary mechanism is the qualitative difference between the functional response of specialist and generalist predators. Second, the interaction between large predators and ungulates is supposed to be prone to lead to two alternative equilibria, one where predation regulates ungulates at a relatively low equilibrium and another, where ungulate densities are close to carrying capacity. In the first‐mentioned issue, our analysis corroborates the general idea of snow favoring specialists and leading to cycles. However, differences in functional response appear to be of secondary importance only, and rather special conditions are required for generalists to have a stabilizing type III functional response. A destabilizing type II functional response or a slight modification of it should be common in generalists, too, as also indicated by the classical experiments. Stability of generalist dominated systems seems primarily to derive from their relative inefficiency, allowing prey's density‐dependent mechanisms to play a bigger role in the neighborhood of the equilibrium. Moreover, the main destabilizing impact of deep, long‐lasting snow cover appears to lie in the protection it offers to the efficient but vulnerable specialists, which are eliminated or marginalized by intraguild predation in areas with snow‐free winters, unless the habitat offers some other form of efficient protection. As for the conjecture of multiple equilibria in northern wolf‐ungulate systems, it seems to be derived from an erroneous operational definition of numerical response and has little if any empirical support. Available data suggest that predation limitation of folivorous mammals prevails along the entire gradient from relatively productive low arctic habitats to the humid parts of the temperate zone, provided that the numbers of predators are not controlled by man.