Martínez-Meyer, E., A. T. Peterson. 2006. Conservatism of ecological niche

characteristics in North American plant species over the

Pleistocene-to-Recent transition. Journal of Biogeography 33: 17791789.

Aim: To provide a test of the conservatism of a species¹ niche over the last

20,000 years by tracking the distribution of eight pollen taxa relative to

climate type as they migrated across eastern North America following the

Last Glacial Maximum (LGM).

Location: North America.

Methods: We drew taxon occurrence data from the North American pollen

records in the Global Pollen Database, representing eight pollen types all

taxa for which „5 distinct geographic occurrences were available in both the

present day and at the LGM (21,000 years ago ± 3000 years). These data were

incorporated into ecological niche models based on present-day and LGM

climatological summaries available from the Palaeoclimate Modelling

Intercomparison Project to produce predicted potential geographic

distributions for each species at present and at the LGM. The output for

each time period was projected onto the Œother¹ time period, and tested

using independent known occurrence information from that period.

Results: The result of our analyses was that all species tested showed

general conservatism in ecological characteristics over the climate changes

associated with the Pleistocene-to-Recent transition.

Main conclusions: This analysis constitutes a further demonstration of

general and pervasive conservatism in ecological niche characteristics over

moderate periods of time despite profound changes in climate and

environmental conditions. As such, our results reinforce the application of

ecological niche modelling techniques to the reconstruction of Pleistocene

biodiversity distribution patterns, and to project the future potential

distribution range of species in the face of global-scale climatic changes.

Peterson, A.T., Á.S. Nyári. 2008. ECOLOGICAL NICHE CONSERVATISM AND

PLEISTOCENE REFUGIA IN THE THRUSH-LIKE MOURNER, SCHIFFORNIS SP., IN THE

NEOTROPICS. Evolution 62:173-183.

Recent studies have increasingly implicated deep (pre-Pleistocene) events as

key in the vertebrate speciation, downplaying the importance of more recent

(Pleistocene) climatic shifts. This work, however, has been based almost

exclusively on evidence from molecular clock inferences of splitting dates.

We present an independent perspective on this question, using ecological

niche model reconstructions of Pleistocene Last Glacial Maximum (LGM)

potential distributions for the Thrush-like Mourner (Schiffornis turdina)

complex in the neotropics. LGM distributional patterns reconstructed from

the niche models relate significantly to phylogroups identified in previous

molecular systematic analyses. As such, patterns of differentiation and

speciation in this complex are consistent with Pleistocene climate and

geography, although further testing will be necessary to establish dates of

origin firmly and unambiguously.

Martínez-Meyer E., A.T. Peterson, W.W. Hargrove. 2004. Ecological niches as

stable distributional constraints on mammal species, with implications for

Pleistocene extinctions and climate change projections for biodiversity.

Global Ecology and Biogeography 13: 305314.

Aim: Theoretical work suggests that species¹ ecological niches should remain

relatively constant over long-term ecological time periods, but empirical

tests are few. We present longitudinal studies of 23 extant mammal species,

modelling ecological niches and predicting geographical distributions

reciprocally between the Last Glacial Maximum and present to test this

evolutionary conservatism.

Location: This study covered distributional shifts in mammal species across

the lower 48 states of the United States.

Methods: We used a machine-learning tool for modelling species¹ ecological

niches, based on known occurrences and electronic maps summarizing

ecological dimensions, to assess the ability of ecological niches as

modelled in one time period to predict the geographical distribution of the

species in another period, and vice versa.

Results: High intertemporal predictivity between niche models and species¹

occurrences indicate that niche conservatism is widespread among the taxa

studied, particularly when statistical power is considered as a reason for

failure of reciprocal predictions. Niche projections to the present for 8

mammal taxa that became extinct at the end of the Pleistocene generally

increased in area, and thus do not support the hypothesis of niche collapse

as a major driving force in their extinction.

Main conclusions: Ecological niches represent long-term stable constraints

on the distributional potential of species; indeed, this study suggests that

mammal species have tracked consistent climate profiles throughout the

drastic climate change events that marked the end of the Pleistocene

glaciations. Many current modelling efforts focusing on anticipating climate

change effects on species¹ potential geographical distributions will be

bolstered by this result ‹ in essence, the first longitudinal demonstration

of niche conservatism.