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Morris, William F.
Publications (5 of 5) Show all publications
Villellas, J., Doak, D. F., Garcia, M. B. & Morris, W. F. (2015). Demographic compensation among populations: what is it, how does it arise and what are its implications?. Ecology Letters, 18(11), 1139-1152
Open this publication in new window or tab >>Demographic compensation among populations: what is it, how does it arise and what are its implications?
2015 (English)In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 18, no 11, p. 1139-1152Article in journal (Refereed) Published
Abstract [en]

Most species are exposed to significant environmental gradients across their ranges, but vital rates (survival, growth, reproduction and recruitment) need not respond in the same direction to those gradients. Opposing vital rate trends across environments, a phenomenon that has been loosely called demographic compensation', may allow species to occupy larger geographical ranges and alter their responses to climate change. Yet the term has never been precisely defined, nor has its existence or strength been assessed for multiple species. Here, we provide a rigorous definition, and use it to develop a strong test for demographic compensation. By applying the test to data from 26 published, multi-population demographic studies of plants, we show that demographic compensation commonly occurs. We also investigate the mechanisms by which this phenomenon arises by assessing which demographic processes and life stages are most often involved. In addition, we quantify the effect of demographic compensation on variation in population growth rates across environmental gradients, a potentially important determinant of the size of a species' geographical range. Finally, we discuss the implications of demographic compensation for the responses of single populations and species' ranges to temporal environmental variation and to ongoing environmental trends, e.g. due to climate change.

Keywords
demographic compensation, environmental gradient, geographical distribution, global climate change, life-history trade-off, negative correlations, population growth rate, range limit, sensitivity, vital rates
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-266683 (URN)10.1111/ele.12505 (DOI)000362915600001 ()
Funder
Swedish Research Council
Available from: 2015-11-13 Created: 2015-11-10 Last updated: 2017-12-01Bibliographically approved
Pironon, S., Villellas, J., Morris, W. F., Doak, D. F. & Garcia, M. B. (2015). Do geographic, climatic or historical ranges differentiate the performance of central versus peripheral populations?. Global Ecology and Biogeography, 24(6), 611-620
Open this publication in new window or tab >>Do geographic, climatic or historical ranges differentiate the performance of central versus peripheral populations?
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2015 (English)In: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 24, no 6, p. 611-620Article in journal (Refereed) Published
Abstract [en]

AimThe centre-periphery hypothesis' (CPH) predicts that species performance (genetics, physiology, morphology, demography) will decline gradually from the centre towards the periphery of the geographic range. This hypothesis has been subjected to continuous debate since the 1980s, essentially because empirical studies have shown contrasting patterns. Moreover, it has been proposed that species performance might not be higher at the geographic range centre but rather at the environmental optimum or at sites presenting greater environmental stability in time. In this paper we re-evaluate the CPH by disentangling the effects of geographic, climatic and historical centrality/marginality on the demography of three widely distributed plant species and the genetic diversity of one of them. LocationEurope and North America. MethodsBased on a species distribution modelling approach, we test whether demographic parameters (vital rates, stochastic population growth rates, density) of three plant species of contrasting life-forms, and the genetic diversity of one of them, are higher at their geographic range centres, climatic optima or projected glacial refugia. ResultsWhile geographic, climatic and historical centre-periphery gradients are often not concordant, overall, none of them explain well the distribution of species demographic performance, whereas genetic diversity responds positively only to a historical centrality, related to post-glacial range dynamics. Main conclusionsTo our knowledge, this is the first assessment of the response of species performance to three centrality gradients, considering all the components of different species life cycles and genetic diversity information across continental distributions. Our results are inconsistent with the idea that geographically, climatically or historically marginal populations generally perform worse than central ones. We particularly emphasize the importance of adopting an interdisciplinary approach in order to understand the relative effects of contemporary versus historical and geographic versus ecological factors on the distribution of species performance.

Keywords
Abundant-centre model, central-marginal hypothesis, climatic niche, genetic diversity, Last Glacial Maximum, latitude, plant demography, population performance, species distribution models
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-255052 (URN)10.1111/geb.12263 (DOI)000354121600001 ()
Available from: 2015-06-22 Created: 2015-06-12 Last updated: 2017-12-04Bibliographically approved
Ehrlen, J. & Morris, W. F. (2015). Predicting changes in the distribution and abundance of species under environmental change. Ecology Letters, 18(3), 303-314
Open this publication in new window or tab >>Predicting changes in the distribution and abundance of species under environmental change
2015 (English)In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 18, no 3, p. 303-314Article, review/survey (Refereed) Published
Abstract [en]

Environmental changes are expected to alter both the distribution and the abundance of organisms. A disproportionate amount of past work has focused on distribution only, either documenting historical range shifts or predicting future occurrence patterns. However, simultaneous predictions of abundance and distribution across landscapes would be far more useful. To critically assess which approaches represent advances towards the goal of joint predictions of abundance and distribution, we review recent work on changing distributions and on effects of environmental drivers on single populations. Several methods have been used to predict changing distributions. Some of these can be easily modified to also predict abundance, but others cannot. In parallel, demographers have developed a much better understanding of how changing abiotic and biotic drivers will influence growth rate and abundance in single populations. However, this demographic work has rarely taken a landscape perspective and has largely ignored the effects of intraspecific density. We advocate a synthetic approach in which population models accounting for both density dependence and effects of environmental drivers are used to make integrated predictions of equilibrium abundance and distribution across entire landscapes. Such predictions would constitute an important step forward in assessing the ecological consequences of environmental changes.

Keywords
Abundance, biotic interactions, climate change, demography, density dependence, environmental drivers, geographical distribution, population model, species distribution model
National Category
Ecology Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-247831 (URN)10.1111/ele.12410 (DOI)000349687500008 ()25611188 (PubMedID)
Available from: 2015-03-30 Created: 2015-03-24 Last updated: 2017-12-04Bibliographically approved
Doak, D. F., Boor, G. K. H., Bakker, V. J., Morris, W. F., Louthan, A., Morrison, S. A., . . . Crowder, L. B. (2015). Recommendations for Improving Recovery Criteria under the US Endangered Species Act. BioScience, 65(2), 189-199
Open this publication in new window or tab >>Recommendations for Improving Recovery Criteria under the US Endangered Species Act
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2015 (English)In: BioScience, ISSN 0006-3568, E-ISSN 1525-3244, Vol. 65, no 2, p. 189-199Article in journal (Refereed) Published
Abstract [en]

Recovery criteria, the thresholds mandated by the Endangered Species Act that define when species may be considered for downlisting or removal from the endangered species list, are a key component of conservation planning in the United States. We recommend improvements in the definition and scientific justification of recovery criteria, addressing both data-rich and data-poor situations. We emphasize the distinction between recovery actions and recovery criteria and recommend the use of quantitative population analyses to measure the impacts of threats and to explicitly tie recovery criteria to population status. To this end, we provide a brief tutorial on the legal and practical requirements and constraints of recovery criteria development. We conclude by contrasting our recommendations with other alternatives and by describing ways in which academic scientists can contribute productively to the planning process and to endangered species recovery.

Keywords
conservation, ecology, population biology, extinction, endangered species
National Category
Ecology Other Biological Topics
Identifiers
urn:nbn:se:uu:diva-246817 (URN)10.1093/biosci/biu215 (DOI)000348973600014 ()
Available from: 2015-03-13 Created: 2015-03-10 Last updated: 2017-12-04Bibliographically approved
Alberts, S. C., Altmann, J., Brockman, D. K., Cords, M., Fedigan, L. M., Pusey, A., . . . Bronikowski, A. M. (2013). Reproductive aging patterns in primates reveal that humans are distinct. Proceedings of the National Academy of Sciences of the United States of America, 110(33), 13440-13445
Open this publication in new window or tab >>Reproductive aging patterns in primates reveal that humans are distinct
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2013 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 110, no 33, p. 13440-13445Article in journal (Refereed) Published
Abstract [en]

Women rarely give birth after similar to 45 y of age, and they experience the cessation of reproductive cycles, menopause, at similar to 50 y of age after a fertility decline lasting almost two decades. Such reproductive senescence in mid-lifespan is an evolutionary puzzle of enduring interest because it should be inherently disadvantageous. Furthermore, comparative data on reproductive senescence from other primates, or indeed other mammals, remains relatively rare. Here we carried out a unique detailed comparative study of reproductive senescence in seven species of nonhuman primates in natural populations, using long-term, individual-based data, and compared them to a population of humans experiencing natural fertility and mortality. In four of seven primate species we found that reproductive senescence occurred before death only in a small minority of individuals. In three primate species we found evidence of reproductive senescence that accelerated throughout adulthood; however, its initial rate was much lower than mortality, so that relatively few individuals experienced reproductive senescence before death. In contrast, the human population showed the predicted and well-known pattern in which reproductive senescence occurred before death for many women and its rate accelerated throughout adulthood. These results provide strong support for the hypothesis that reproductive senescence in midlife, although apparent in natural-fertility, natural-mortality populations of humans, is generally absent in other primates living in such populations.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-206969 (URN)10.1073/pnas.1311857110 (DOI)000323069200056 ()
Available from: 2013-09-09 Created: 2013-09-09 Last updated: 2017-12-06Bibliographically approved
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