TY - BOOK
T1 - A niche-based perspective on the response of Palearctic mammals to climate change and human impact
AU - Giampoudakis, Konstantinos
PY - 2018
Y1 - 2018
N2 - The fast pace of socioeconomic growth in the past decades has left its footprint on biodiversity
and all its components (genes, species and ecosystems), endangering biosphere integrity and
human survival [1]. Extinction is a natural phenomenon that is part of life on Earth but is
balanced by speciation [2, 3]. The large extinction events that have depleted Earth of the
majority of its biota, are rare events (only five have been recorded in the last 540Mya) [4] with
different natural causes acting to affect Earths global system (e.g. glaciations, asteroid
collisions or eruption of super-volcanos). Contemporary extinctions though, are caused mainly
by human activities, e.g. habitat fragmentation and changing climate among others, and these
are occurring at an unprecedented rate and scale [5]. The “Anthropocene defaunation” is both
result and a force of global change [6], with potential cascade effects at a planetary scale [7].
Quantitative assessments regarding the loss of species and alteration of natural habitat show
that extinction rates and magnitude surpass background rates by far, even those of past massextinction
events [8]. To predict and limit the loss of the remaining biodiversity we need to
evaluate how environmental changes affect species survival, their distributions and potential
to adapt.
The Late Pleistocene (126ka-11.7ka; 1ka=1,000 years ago) was characterized by a peculiar
extinction event, that witnessed a large and global extinction of mainly large bodied (> 45kg)
mammal genera (101 out of ~150) [9]. Both the expansion of H. sapiens hunter-gatherers and
large climatic changes have been hypothesized to be the main causes of this extinction event
[10-17].
The main aim of this thesis is to evaluate the role of climate and associated environmental
changes in the changing distribution of mammals, including Anatomically Modern Humans
(AMH: H. sapiens), and its potential effects on past local/global extinctions. By treating AMHs
as another megafauna species, we gain insights as to how they managed to be so successful in
colonizing most parts of the globe but also how they impacted the mammalian assemblages
that they encountered during their expansion across the Palaearctic. Lastly, we show how these
data and methods can be used to revaluate past hypothesis on population collapses, extinction
and extirpation events across large spatial, temporal and taxonomic scales.
To achieve the goals of this thesis I collated a database of H. sapiens fossil material across the
Palaearctic during the Late Pleistocene to Holocene transition (50ka-9ka) and a fossil database
of 15 mammal species which were present in the Palearctic during that period. I also used high
temporal resolution palaeoclimatic (Chapters 1&2) and palaeo-vegetation (Chapter 3)
reconstructions, to characterise the climatic and habitat preference (ecological niche) of
mammal species and estimate their potential distributions. Utilizing traditional niche-based
concepts and macroecological tools I reconstructed the historical biogeography of this set
mammal species including AMHs.
My research shows that the realised climatic niche of mammal taxa, including modern humans,
is changing across time (Chapters 1&2) and space (Chapter 3). Although these changes are
highly individualistic, they reveal some common patterns across body mass categories and
feeding guilds. An interesting finding is that the breadth of the climatic niche, or the
specialization in climatic conditions a species can persist in, is not indicative of the potential
for a species to survive or go extinct. A probable explanation is that the decreasing niche
breadth occupied by species (Chapters 1&2) is the result of loss of populations inhabiting
specific conditions across space (Chapter 3), which also contribute to a species genetic
diversity, thereby affecting its ability to adapt in large scale changes at the population level.
This is not the case for modern humans, who after an initial dramatic increase of their climatic
niche accompanied by range expansion were not affected by a subsequent niche breadth
contraction (Chapter 1), potentially due to their remarkable adaptability by technological
innovations in different conditions. My results do not support direct impacts of humans on the
extinction of iconic megaherbivores, i.e. the woolly rhino and the woolly mammoth, but a mild
effect on large top predators by competitive exclusion.
In summary, this thesis improves our understanding on species responses to anthropogenic and
other disturbances and it sheds new light on the factors triggering or buffering biodiversity
declines. Moreover, it stresses the importance of re-evaluating widely accepted hypothesis on
species exposure to extinction in light of new data, methods, concepts and interdisciplinary
approaches.
AB - The fast pace of socioeconomic growth in the past decades has left its footprint on biodiversity
and all its components (genes, species and ecosystems), endangering biosphere integrity and
human survival [1]. Extinction is a natural phenomenon that is part of life on Earth but is
balanced by speciation [2, 3]. The large extinction events that have depleted Earth of the
majority of its biota, are rare events (only five have been recorded in the last 540Mya) [4] with
different natural causes acting to affect Earths global system (e.g. glaciations, asteroid
collisions or eruption of super-volcanos). Contemporary extinctions though, are caused mainly
by human activities, e.g. habitat fragmentation and changing climate among others, and these
are occurring at an unprecedented rate and scale [5]. The “Anthropocene defaunation” is both
result and a force of global change [6], with potential cascade effects at a planetary scale [7].
Quantitative assessments regarding the loss of species and alteration of natural habitat show
that extinction rates and magnitude surpass background rates by far, even those of past massextinction
events [8]. To predict and limit the loss of the remaining biodiversity we need to
evaluate how environmental changes affect species survival, their distributions and potential
to adapt.
The Late Pleistocene (126ka-11.7ka; 1ka=1,000 years ago) was characterized by a peculiar
extinction event, that witnessed a large and global extinction of mainly large bodied (> 45kg)
mammal genera (101 out of ~150) [9]. Both the expansion of H. sapiens hunter-gatherers and
large climatic changes have been hypothesized to be the main causes of this extinction event
[10-17].
The main aim of this thesis is to evaluate the role of climate and associated environmental
changes in the changing distribution of mammals, including Anatomically Modern Humans
(AMH: H. sapiens), and its potential effects on past local/global extinctions. By treating AMHs
as another megafauna species, we gain insights as to how they managed to be so successful in
colonizing most parts of the globe but also how they impacted the mammalian assemblages
that they encountered during their expansion across the Palaearctic. Lastly, we show how these
data and methods can be used to revaluate past hypothesis on population collapses, extinction
and extirpation events across large spatial, temporal and taxonomic scales.
To achieve the goals of this thesis I collated a database of H. sapiens fossil material across the
Palaearctic during the Late Pleistocene to Holocene transition (50ka-9ka) and a fossil database
of 15 mammal species which were present in the Palearctic during that period. I also used high
temporal resolution palaeoclimatic (Chapters 1&2) and palaeo-vegetation (Chapter 3)
reconstructions, to characterise the climatic and habitat preference (ecological niche) of
mammal species and estimate their potential distributions. Utilizing traditional niche-based
concepts and macroecological tools I reconstructed the historical biogeography of this set
mammal species including AMHs.
My research shows that the realised climatic niche of mammal taxa, including modern humans,
is changing across time (Chapters 1&2) and space (Chapter 3). Although these changes are
highly individualistic, they reveal some common patterns across body mass categories and
feeding guilds. An interesting finding is that the breadth of the climatic niche, or the
specialization in climatic conditions a species can persist in, is not indicative of the potential
for a species to survive or go extinct. A probable explanation is that the decreasing niche
breadth occupied by species (Chapters 1&2) is the result of loss of populations inhabiting
specific conditions across space (Chapter 3), which also contribute to a species genetic
diversity, thereby affecting its ability to adapt in large scale changes at the population level.
This is not the case for modern humans, who after an initial dramatic increase of their climatic
niche accompanied by range expansion were not affected by a subsequent niche breadth
contraction (Chapter 1), potentially due to their remarkable adaptability by technological
innovations in different conditions. My results do not support direct impacts of humans on the
extinction of iconic megaherbivores, i.e. the woolly rhino and the woolly mammoth, but a mild
effect on large top predators by competitive exclusion.
In summary, this thesis improves our understanding on species responses to anthropogenic and
other disturbances and it sheds new light on the factors triggering or buffering biodiversity
declines. Moreover, it stresses the importance of re-evaluating widely accepted hypothesis on
species exposure to extinction in light of new data, methods, concepts and interdisciplinary
approaches.
UR - https://rex.kb.dk/primo-explore/fulldisplay?docid=KGL01011005974&context=L&vid=NUI&search_scope=KGL&tab=default_tab&lang=da_DK
M3 - Ph.D. thesis
BT - A niche-based perspective on the response of Palearctic mammals to climate change and human impact
PB - Natural History Museum of Denmark, Faculty of Science, University of Copenhagen
ER -
