ORCID Profile
0000-0001-5112-2508
Current Organisation
University of Nebraska-Lincoln
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Palaeoecology | Ecology | Conservation and Biodiversity
Expanding Knowledge in the Biological Sciences | Flora, Fauna and Biodiversity at Regional or Larger Scales | Expanding Knowledge in History and Archaeology |
Publisher: Proceedings of the National Academy of Sciences
Date: 04-01-2021
Abstract: Mammals on landscapes within North America are now living in different climates than they did prior to major human expansions. Many smaller animals have expanded into climates now dominated by agricultural and urban regions whereas large-bodied mammals were forced out of these climates and were relegated to colder, dryer regions. As a result, the distributions of modern mammals do not accurately reflect the range of climatological conditions where species can live. Rather, they reflect the marginalization or facilitation that those species have undergone following the expansion of major human activities. Failing to mitigate the ecological changes that mammals are experiencing can have unprecedented impacts on the future survival of the remaining large-bodied species in North America.
Publisher: University of Chicago Press
Date: 05-2004
DOI: 10.1086/382898
Publisher: American Association for the Advancement of Science (AAAS)
Date: 20-09-2019
Abstract: Large mammals are at high risk of extinction globally. To understand the consequences of their demise for community assembly, we tracked community structure through the end-Pleistocene megafaunal extinction in North America. We decomposed the effects of biotic and abiotic factors by analyzing co-occurrence within the mutual ranges of species pairs. Although shifting climate drove an increase in niche overlap, co-occurrence decreased, signaling shifts in biotic interactions. Furthermore, the effect of abiotic factors on co-occurrence remained constant over time while the effect of biotic factors decreased. Biotic factors apparently played a key role in continental-scale community assembly before the extinctions. Specifically, large mammals likely promoted co-occurrence in the Pleistocene, and their loss contributed to the modern assembly pattern in which co-occurrence frequently falls below random expectations.
Publisher: Society for Sedimentary Geology
Date: 05-2011
Publisher: Research Square Platform LLC
Date: 22-09-2022
DOI: 10.21203/RS.3.RS-2054778/V1
Abstract: Ecological interactions help determine the distribution of species across landscapes and play crucial roles in ecosystem services such as pollination, seed dispersal, and pest control1. Human disturbances, particularly habitat alteration, have the potential to modify or erase ecological interactions2,3 and so jeopardise the processes they control. While ex les of interactions becoming rewired under human influence have been recorded, studies of this process for speciose assemblages at regional to continental scales are uncommon4 and obstructed by logistical difficulties2. The consequences for ecological communities and people are therefore poorly understood. Here we show that human habitat alteration is associated with a decrease in the spatial aggregation of Neotropical bat pairs and bird pairs that share similar dietary requirements. We find that groups of species pairs with similar vs. different diets have positive spatial associations on average, but pairs within dietary guilds have stronger associations than pairs with disparate diets when habitats are relatively intact. Our results suggest that species with similar resource requirements typically coexist in relatively intact natural settings. By contrast, exclusion becomes more common (though not dominant) when habitats are altered. Altered habitats thus fail to support the coexistence of erse competitive interactions, reversing patterns observed in the wild.
Publisher: Wiley
Date: 06-08-2013
DOI: 10.1111/JBI.12196
Publisher: The Royal Society
Date: 07-06-2014
Abstract: There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of in idual clades. Here, we investigate the temporal distribution of maximum size observed within in idual orders globally and on separate continents. While the maximum size of in idual orders of large land mammals show differences and comprise several families, the times at which orders reach their maximum size over time show strong congruence, peaking in the Middle Eocene, the Oligocene and the Plio-Pleistocene. The Eocene peak occurs when global temperature and land mammal ersity are high and is best explained as a result of niche expansion rather than abiotic forcing. Since the Eocene, there is a significant correlation between maximum size frequency and global temperature proxy. The Oligocene peak is not statistically significant and may in part be due to s ling issues. The peak in the Plio-Pleistocene occurs when global temperature and land mammal ersity are low, it is statistically the most robust one and it is best explained by global cooling. We conclude that the macroevolutionary patterns observed are a result of the interplay between eco-evolutionary processes and abiotic forcing.
Publisher: The Royal Society
Date: 07-08-2013
Abstract: Body size affects nearly all aspects of organismal biology, so it is important to understand the constraints and dynamics of body size evolution. Despite empirical work on the macroevolution and macroecology of minimum and maximum size, there is little general quantitative theory on rates and limits of body size evolution. We present a general theory that integrates in idual productivity, the lifestyle component of the slow–fast life-history continuum, and the allometric scaling of generation time to predict a clade's evolutionary rate and asymptotic maximum body size, and the shape of macroevolutionary trajectories during ersifying phases of size evolution. We evaluate this theory using data on the evolution of clade maximum body sizes in mammals during the Cenozoic. As predicted, clade evolutionary rates and asymptotic maximum sizes are larger in more productive clades (e.g. baleen whales), which represent the fast end of the slow–fast lifestyle continuum, and smaller in less productive clades (e.g. primates). The allometric scaling exponent for generation time fundamentally alters the shape of evolutionary trajectories, so allometric effects should be accounted for in models of phenotypic evolution and interpretations of macroevolutionary body size patterns. This work highlights the intimate interplay between the macroecological and macroevolutionary dynamics underlying the generation and maintenance of morphological ersity.
Publisher: Informa UK Limited
Date: 03-2014
Publisher: Proceedings of the National Academy of Sciences
Date: 30-01-2012
Abstract: How fast can a mammal evolve from the size of a mouse to the size of an elephant? Achieving such a large transformation calls for major biological reorganization. Thus, the speed at which this occurs has important implications for extensive faunal changes, including adaptive radiations and recovery from mass extinctions. To quantify the pace of large-scale evolution we developed a metric, clade maximum rate, which represents the maximum evolutionary rate of a trait within a clade. We applied this metric to body mass evolution in mammals over the last 70 million years, during which multiple large evolutionary transitions occurred in oceans and on continents and islands. Our computations suggest that it took a minimum of 1.6, 5.1, and 10 million generations for terrestrial mammal mass to increase 100-, and 1,000-, and 5,000-fold, respectively. Values for whales were down to half the length (i.e., 1.1, 3, and 5 million generations), perhaps due to the reduced mechanical constraints of living in an aquatic environment. When differences in generation time are considered, we find an exponential increase in maximum mammal body mass during the 35 million years following the Cretaceous–Paleogene (K–Pg) extinction event. Our results also indicate a basic asymmetry in macroevolution: very large decreases (such as extreme insular dwarfism) can happen at more than 10 times the rate of increases. Our findings allow more rigorous comparisons of microevolutionary and macroevolutionary patterns and processes.
Publisher: Wiley
Date: 08-10-2020
DOI: 10.1111/ECOG.05027
Abstract: The late Quaternary of North America was marked by prominent ecological changes, including the end‐Pleistocene megafaunal extinction, the spread of human settlements and the rise of agriculture. Here we examine the mechanistic reasons for temporal changes in mammal species association and body size during this time period. Building upon the co‐occurrence results from Lyons et al. (2016) – wherein each species pair was classified as spatially aggregated, segregated or random – we examined body mass differences (BMD) between each species pair for each association type and time period (Late Pleistocene: 40 000 14 C–11 700 14 C ybp, Holocene: 11 700 14 C–50 ybp and Modern: 50–0 yr). In the Late Pleistocene and Holocene, the BMD of both aggregated and segregated species pairs was significantly smaller than the BMD of random pairs. These results are consistent with environmental filtering and competition as important drivers of community structure in both time periods. Modern assemblages showed a breakdown between BMD and co‐occurrence patterns: the average BMD of aggregated, segregated and random species pairs did not differ from each other. Collectively, these results indicate that the late Quaternary mammalian extinctions not only eliminated many large‐bodied species but were followed by a re‐organization of communities that altered patterns of species coexistence and associated differences in body size.
Publisher: Springer Science and Business Media LLC
Date: 16-12-2015
DOI: 10.1038/NATURE16447
Abstract: Understanding how ecological communities are organized and how they change through time is critical to predicting the effects of climate change. Recent work documenting the co-occurrence structure of modern communities found that most significant species pairs co-occur less frequently than would be expected by chance. However, little is known about how co-occurrence structure changes through time. Here we evaluate changes in plant and animal community organization over geological time by quantifying the co-occurrence structure of 359,896 unique taxon pairs in 80 assemblages spanning the past 300 million years. Co-occurrences of most taxon pairs were statistically random, but a significant fraction were spatially aggregated or segregated. Aggregated pairs dominated from the Carboniferous period (307 million years ago) to the early Holocene epoch (11,700 years before present), when there was a pronounced shift to more segregated pairs, a trend that continues in modern assemblages. The shift began during the Holocene and coincided with increasing human population size and the spread of agriculture in North America. Before the shift, an average of 64% of significant pairs were aggregated after the shift, the average dropped to 37%. The organization of modern and late Holocene plant and animal assemblages differs fundamentally from that of assemblages over the past 300 million years that predate the large-scale impacts of humans. Our results suggest that the rules governing the assembly of communities have recently been changed by human activity.
Publisher: Springer Science and Business Media LLC
Date: 31-08-2016
DOI: 10.1038/NATURE19110
Start Date: 2021
End Date: 12-2023
Amount: $391,000.00
Funder: Australian Research Council
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