The geographic variation of taxonomic richness may be directly determined by climate through contemporaneous/ecological processes, versus other (e.g., historical/evolutionary processes) that happen to be collinear with contemporaneous climate. In Chapter 1 I evaluated hypotheses from both groups of explanations in North America. If contemporaneous climate controls patterns of richness, then richness should vary with climate through time in the same way that richness varies with current climate through space. Over the last ca. 11,000 yr, richness-temperature relationships remained reasonably constant. Between 12,000 and 14,000 yr BP, when climate fluctuated rapidly, richness gradients as a function of temperature were significantly shallower. If historical climate over the last 21,000 years determines patterns of richness, then historical climate should be a better predictor of richness than contemporaneous climate. I rejected historical-climate as a better predictor of richness. Contemporaneous climate stands as the most plausible explanation for contemporaneous patterns of richness, at least over the last 11,000 yr. In Chapter two, I tested the prediction that richness of most taxa should increase with temperature in all but the warmest and driest areas. Climate warming during Pleistocene-Holocene transition led richness increases in wet areas, but richness declines in dry regions, as expected from current richness-climate relationships. A decline in small mammal species richness in Northern California since the late Pleistocene was expected from the current richness-climate relationship for this group in North America. These results contest the view that future global warming may lead to species extinction rates that would qualify as the sixth mass extinction in the history of the earth. In chapter three, I first tested the hypothesis that richness gradients mainly reflect the sum of individual species climatic tolerances. I tested this hypothesis for birds, mammals and trees native to eastern North America (ENA, where there are no major barriers to dispersal). The number of species present in any given area in ENA is usually much smaller than the number of species in the continental pool that tolerate the climatic conditions in that area. Second, I tested several explanations for patterns of unfilled potential richness. Unfilled potential richness is inconsistent with postglacial dispersal lags, climatic variability since the Last Glacial Maximum, or with biotic interactions. In contrast, unfilled richness is highly consistent with a probabilistic model of species climate occupancy. Individual species climatic tolerances is not the process generating the main current patterns of richness, nor are post-glacial dispersal lags, climatic variability since the LGM or biotic interactions. This thesis is consistent with the hypothesis that contemporaneous climate directly controls spatial patterns of richness. Generally, there seems to be little need to invoke historical processes as determinants of current gradients of richness.

Bulbuls (Pycnonotidae) are a biologically diverse group of songbirds that produce a variety of vocalisations. Their songs are very audible, yet the vocal behaviour of the majority of bulbul species has not been formally described or subject to bioacoustical study. The Philippine bulbul (Ixos philippinus) is a sedentary and endemic species of the Philippine archipelago. This thesis presents the first detailed descriptions of its song. The songs were recorded on five islands locations that covered eight different habitats. Nine song features of these species were compared, in order to understand song variations between different islands. In searching for correlations, habitat types and geographical distances between the islands were also measured. The songs of the species found on five islands were readily split up into three groups based on end frequency, syllable number and song duration. The correlations possibly relate to a late Pleistocene connection between the islands and colonization routes of the species. It was found that song frequency parameters in bulbul species is primarily affected by habitat, whilst the effect of current distances between islands was shown to be weak.

The Rancholabrean Land Mammal Age (RLB) occurred in the late Pleistocene, incorporating at least the Wisconsin Glaciation and possibly the preceding interglacial ('Sangamon'). The RLB is defined based on the occurrence of Bison. The first occurrence (arrival time) of Bison is not well established and is still debated. A conservative approach toward the RLB includes: (1) restricting the RLB to faunas south of 55°. N latitude in North America, (2) defining the RLB by the earliest arrival of Bison south of this latitude, (3) placing the best-corroborated arrival time of Bison (therefore the beginning of the RLB) between approximately 210 and 160. ka, and (4) the end of the RLB is marked by the extinction of mainly large mammals as an event or process culminating at approximately 11 radiocarbon ka BP. RLB faunas contain a wealth of information including amphibians, reptiles, birds, and mammals, but clearly the most is known about the latter. Glacial climate regimes forced species into communities that do not occur today (nonanalog or disharmonious scenarios). The debate about the terminal RLB extinctions continues with the cause either being (1) overkill due to the arrival of the First Americans, or (2) the climatic and environmental defragmentation of biotic communities.

The Rancholabrean Land Mammal Age (RLB) occurred in the late Pleistocene, incorporating at least the Wisconsin Glaciation and possibly the preceding interglacial ('Sangamon'). The RLB is defined based on the occurrence of Bison. The first occurrence (arrival time) of Bison is not well established and is still debated. A conservative approach toward the RLB includes: (1) restricting the RLB to faunas south of 55°. N latitude in North America, (2) defining the RLB by the earliest arrival of Bison south of this latitude, (3) placing the best-corroborated arrival time of Bison (therefore the beginning of the RLB) between approximately 210 and 160. ka, and (4) the end of the RLB is marked by the extinction of mainly large mammals as an event or process culminating at approximately 11 radiocarbon ka BP. RLB faunas contain a wealth of information including amphibians, reptiles, birds, and mammals, but clearly the most is known about the latter. Glacial climate regimes forced species into communities that do not occur today (nonanalog or disharmonious scenarios). The debate about the terminal RLB extinctions continues with the cause either being (1) overkill due to the arrival of the First Americans, or (2) the climatic and environmental defragmentation of biotic communities.

No description available.

Recent concern over the effects of ocean acidification upon calcifying organisms in the modern ocean has highlighted the aragonitic shelled thecosomatous pteropods as being at a high risk. Laboratory studies have shown that increased pCO2, leading to decreased pH and low carbonate concentrations, has a negative impact on the ability of pteropods to calcify and maintain their shells. This study presents the micropalaeontological analysis of marine cores from the Caribbean Sea, Mediterranean Sea and Indian Ocean. Pteropods, heteropods and planktic foraminifera were picked from samples to provide palaeoenvironmental data for each core. Determination of pteropod calcification was made using the Limacina Dissolution Index (LDX) and the average shell size of Limacina inflata specimens. Pteropod calcification indices were compared to global ice volume and Vostok atmospheric CO2 concentrations to determine any associations between climate and calcification. Results show that changes in surface ocean carbonate concentrations throughout the Late Pleistocene did affect the calcification of thecosomatous pteropods. These effects can be detected in shells from marine sediments that are located well above the aragonite lysocline and have not undergone post-depositional dissolution. The results of this study confirm the findings of laboratory studies, showing a decrease in calcification during interglacial periods, when surface ocean carbonate concentrations were lower. During glacial periods, calcification was enhanced due to the increased availability of carbonate. This trend was found in all sediments studied, indicating that the response of pteropods to past climate change is of global significance. These results demonstrate that pteropods have been negatively affected by oceanic pH levels relatively higher and changing at a lesser rate than those predicted for the 21st Century. Results also establish the use of pteropods and heteropods in reconstructing surface ocean conditions. The LDX is a fast and appropriate way of determining variations in surface water carbonate saturation. Abundances of key species were also found to constrain palaeotemperatures better than planktic foraminifera, a use which could be further developed.

Until relatively recently, the view of Late Pleistocene hunter-gatherers in the Americas was dominated by the “Clovis-first” paradigm. However, recent discoveries have challenged traditional views and forced reconsiderations of the timing, processes, and scales used in modeling the settlement of the Americas. Chief among these discoveries has been the recognition of a wide range of early cultural diversity throughout the Americas that is inconsistent with previously held notions of cultural homogeneity. During the Late Pleistocene-Early Holocene, the development of widely varying economic, technological and mobility strategies in distinct environments is suggestive of a range of different adaptations and traditions. It is argued that colonization was a disjointed process involving alternative, perhaps competing strategies at local and regional levels. Individual groups likely employed distinct strategies for settling new landscapes. These different strategies are reflected in the cultural variability that has been documented in the Late Pleistocene-Early Holocene archaeological records of South and North America. A scalar framework for conceptualizing and modeling this variability on local, regional, and continental scales is introduced. Although primarily focused on local and regional reconstructions, the results can be integrated with other regional studies to generate more comprehensive, continental-scale models of the peopling of the New World. This research provides insight into the local and regional variability—in terms of settlement patterns and economic and technological strategies—present in the archaeological record of at least two formally recognized Late Pleistocene-Early Holocene complexes (Fishtail and Paiján complexes) in the Quebradas del Batán and Talambo of the lower Jequetepeque Valley, northern Perú. Results of extensive survey, excavation, and materials analyses are used to characterize mobility strategies and settlement organization. This research indicates that two distinct patterns of site types, settlement, subsistence, and technology existed at the local level between the Fishtail (ca. 11,200-10,200 B.P.) and Paiján (ca. 10,800-9,000 B.P.); these patterns are indicative of differing regional strategies of colonization. Lastly, it is suggested that the adaptations and behaviors pursued during regional settlement, particularly by Paiján groups, set in motion an increasing reliance on plant foods and an early trend toward sedentism that carried forward into the Holocene period.

Os roedores Hystricognathi da América do Sul formam um grupo monofilético, os Caviomorpha. Estes roedores provavelmente são derivados de ancestrais africanos e chegaram ao continente sul-americano em algum momento do Eoceno. Devido ao longo período de isolamento geográfico, os caviomorfos atingiram uma grande diversidade fenotípica e ecológica, com mais de 160 gêneros fósseis e viventes. Neste trabalho, é revisado o conhecimento sobre o registro fóssil deste grupo no Pleistoceno do Rio Grande do Sul (RS), sul do Brasil; descrito novo material e discutido suas implicações paleoambientais e paleobiogeográficas. Desta forma, os principais resultados são: 1 – Reporta-se pela primeira vez a ocorrência de Galea e Lagostomus cf. L. maximus no Pleistoceno final do sul do Brasil, sendo que este último táxon representa o primeiro registro de um Chinchillidae no Brasil. 2 – Descreve-se materiais de Hydrochoerus hydrochaeris; 3 – Reporta-se novos materiais de Dolichotinae e Myocastor de depósitos continentais, confirmando sua presença durante o Pleistoceno final desta região; 4 – Os caviomorfos pleistocênicos do RS apresentam afinidade paleobiogrográfica mais acentuada com a paleofauna do Uruguai; 5 – Os indicativos paleoambientais dos caviomorfos suportam modelos previamente hipotetizados de áreas abertas durante o Pleistoceno final, substituídas por vegetação florestal durante o Holoceno. 6 – Durante a transição Pleistoceno final/Holoceno, observa-se a extinção regional de táxons com afinidade às áreas abertas, como Microcavia, Galea, Dolichotinae e Lagostomus, substituídos por uma predominância de táxons de afinidade florestal durante o Holoceno. / The Hystricognathi rodents from South America are a monophyletic group, the Caviomorpha. These rodents are probably derived from African ancestors and they arrived in South America during the Eocene. Due to the long period of geographic isolation, the caviomorphs achieved great ecologic and phenotypic diversity, with more than 160 living and fossil genera. In this work, we revised the knowledge on the Pleistocene fossil record of caviomorphs from Rio Grande do Sul State (RS), southern Brazil; described new remains and discussed their paleobiogeographic and paleoenvironmental implications. Thus, the main results are: 1 – We reported, for the first time, the occurrence of Galea and Lagostomus cf. L. maximus in the late Pleistocene of the southern Brazil. The record of Lagostomus is the first occurrence of Chinchillidae in Brazil; 2 – We described remains of Hydrochoerus hydrochaeris. 3 – We reported new remains of Dolichotinae and Myocastor from continental deposits, confirming their presence in the late Pleistocene of this region; 4 – The RS caviomorphs show paleozoogeographic affinities with the late Pleistocene from Uruguay; 5 – The paleoenvironmental indicatives of caviomorphs corroborate the previous interpretations of open areas during the late Pleistocene substituted by forest areas in the Holocene; 6 – During the late Pleistocene/Holocene transition we observed a local extinction of taxa with open areas affinities, as Microcavia, Galea, Dolichotinae and Lagostomus, substituted by a predominance of taxa typical of forested areas during the Holocene.

This project examines small mammal faunas from cave sites in south-west England and south Wales. The aims are threefold: To examine the rapid environmental changes taking place in the Late Pleistocene and early Holocene: To understand the processes by which small mammal remains were deposited in the caves examined: To demonstrate the value of small mammal studies as an archaeological tool. All identifiable small mammal remains from twelve selected sites are listed. Ten of the sites are new material. As the species examined here are seldom exploited by humans, the small mammals provide a record of the past environment unaffected by human selection of particular species, as might be the case in larger mammal assemblages. An examination of possible agents of accumulation is provided for each site to identify any bias introduced by prey selection. Reconstructions of the environment local to each cave at the time of deposition are offered. The evidence provided by the small mammals is related to the archaeological findings from each cave, to demonstrate the effect of human habitation of cave sites on the depositional and post-depositional processes shown by the microfauna. The environmental evidence provided by the study reflects a wider landscape rather than merely the immediate surroundings of the cave, and so gives a basis for human exploitation patterns in the area accessible from the cave. Reconstructions of the ecological mosaics formed by the rapidly changing climate of the period and the topographic variation around the cave sites are provided, demonstrating the potential complexity of the environment in which the humans and other fauna of the period existed. It is hoped that this will encourage archaeologists to look beyond the general division of environmental boundaries in this period, and to examine the local variation in habitat availability and use.

Os roedores Hystricognathi da América do Sul formam um grupo monofilético, os Caviomorpha. Estes roedores provavelmente são derivados de ancestrais africanos e chegaram ao continente sul-americano em algum momento do Eoceno. Devido ao longo período de isolamento geográfico, os caviomorfos atingiram uma grande diversidade fenotípica e ecológica, com mais de 160 gêneros fósseis e viventes. Neste trabalho, é revisado o conhecimento sobre o registro fóssil deste grupo no Pleistoceno do Rio Grande do Sul (RS), sul do Brasil; descrito novo material e discutido suas implicações paleoambientais e paleobiogeográficas. Desta forma, os principais resultados são: 1 – Reporta-se pela primeira vez a ocorrência de Galea e Lagostomus cf. L. maximus no Pleistoceno final do sul do Brasil, sendo que este último táxon representa o primeiro registro de um Chinchillidae no Brasil. 2 – Descreve-se materiais de Hydrochoerus hydrochaeris; 3 – Reporta-se novos materiais de Dolichotinae e Myocastor de depósitos continentais, confirmando sua presença durante o Pleistoceno final desta região; 4 – Os caviomorfos pleistocênicos do RS apresentam afinidade paleobiogrográfica mais acentuada com a paleofauna do Uruguai; 5 – Os indicativos paleoambientais dos caviomorfos suportam modelos previamente hipotetizados de áreas abertas durante o Pleistoceno final, substituídas por vegetação florestal durante o Holoceno. 6 – Durante a transição Pleistoceno final/Holoceno, observa-se a extinção regional de táxons com afinidade às áreas abertas, como Microcavia, Galea, Dolichotinae e Lagostomus, substituídos por uma predominância de táxons de afinidade florestal durante o Holoceno. / The Hystricognathi rodents from South America are a monophyletic group, the Caviomorpha. These rodents are probably derived from African ancestors and they arrived in South America during the Eocene. Due to the long period of geographic isolation, the caviomorphs achieved great ecologic and phenotypic diversity, with more than 160 living and fossil genera. In this work, we revised the knowledge on the Pleistocene fossil record of caviomorphs from Rio Grande do Sul State (RS), southern Brazil; described new remains and discussed their paleobiogeographic and paleoenvironmental implications. Thus, the main results are: 1 – We reported, for the first time, the occurrence of Galea and Lagostomus cf. L. maximus in the late Pleistocene of the southern Brazil. The record of Lagostomus is the first occurrence of Chinchillidae in Brazil; 2 – We described remains of Hydrochoerus hydrochaeris. 3 – We reported new remains of Dolichotinae and Myocastor from continental deposits, confirming their presence in the late Pleistocene of this region; 4 – The RS caviomorphs show paleozoogeographic affinities with the late Pleistocene from Uruguay; 5 – The paleoenvironmental indicatives of caviomorphs corroborate the previous interpretations of open areas during the late Pleistocene substituted by forest areas in the Holocene; 6 – During the late Pleistocene/Holocene transition we observed a local extinction of taxa with open areas affinities, as Microcavia, Galea, Dolichotinae and Lagostomus, substituted by a predominance of taxa typical of forested areas during the Holocene.