Evolutionary Ecology

Exploring the functional association between physiological plasticity, climatic variability, and geographical latitude: Lessons from land snails

by Juan Diego Gaitán-Espitia

Co-authored with Daniel Naya, T. Catalan, P. Artacho and R. Nespolo.
Evolutionary Ecology Research, 2011

Background: The climatic variability hypothesis states that, as the range of climatic
fluctuation experienced by... more Background: The climatic variability hypothesis states that, as the range of climatic
fluctuation experienced by terrestrial animals increases with latitude, individuals at higher latitudes should be more plastic than individuals inhabiting lower latitudes. However, it is unclear whether comparatively high flexibility at higher latitudes is due to the direct effect of climatic variability or to other factors associated with latitude. Aim: To investigate the relationship between phenotypic flexibility, geographical latitude, and
climatic variability using a dataset where latitude and climatic variability are inversely related. Methods: We assessed the physiological plasticity to cope with thermal change (10C vs.
20C), at the level of metabolic rate and organ dry weight, in three populations of the brown garden snail (Cornu aspersum): Viña del Mar (3320S, 7132W), with high temperature and rainfall variability; Concepción (3647S, 737W), with a narrow range of temperature variability and intermediate rainfall variability; and Valdivia (3938S, 735W), with low temperature and rainfall variability. Results: Standard metabolic rate was higher at 20C than at 10C, but did not differ between
populations. Intestine dry weight did not differ among populations but it was higher at 20C than at 10C, particularly for individuals from the Viña del Mar and Conception populations. Hepatopancreas and kidney dry weight differed between populations, which was due to higher values in Viña del Mar at 20C. Conclusions: Flexibility in the weight of the organs analysed changed in a similar fashion
to annual temperature variation at each locality, suggesting that, as stated by the climatic variability hypothesis, climatic variability is the main force behind physiological plasticity.

Repeatability of energy metabolism and resistance to dehydration in the invasive slug Limax maximus

by Juan Diego Gaitán-Espitia

Invertebrate Biology, Volume 131, Issue 1, pages 11–18, March 2012

Standard metabolic rate (SMR) and resistance to body dehydration (BD) are important physiological traits that have an... more Standard metabolic rate (SMR) and resistance to body dehydration (BD) are important physiological traits that have an effect on water balance and the amount of energy available for activity and production, and thus could contribute to variation in life history traits expressed across a range of environments. Few studies have tested whether SMR and BD show consistent between-individual variation in molluscs. Significant repeatability of SMR and BD indicates that the traits might be heritable and therefore a possible target for natural selection, so describing the repeatability of SMR and BD is important in studies of phenotypic variability. Here, we studied energy metabolism (body mass-corrected SMR) and the change in the scaling relationship of SMR and body mass in response to time between measurements in the giant garden slug Limax maximus. Limax maximus is one of the most invasive terrestrial molluscs, with a wide geographical distribution, and is considered an important pest of horticultural and agricultural crops. Our results show that L. maximus follows the expected relationship of increasing SMR with increasing mass, but the scaling exponent varies through time and is different from that described for other gastropods. We also found significant inter-individual variation in VCO2 Mean, VCO2 Min, VCO2 Max, and BD (τ=0.25, 0.29, 0.24, 0.22, p<0.05, respectively), and significant repeatability of body mass (τ=0.90). To our knowledge, this is the first comprehensive analysis of the repeatability of body mass-corrected SMR and BD in terrestrial slugs. Our results suggest that energy metabolism and water balance could potentially respond to selection.

Within-genotype epigenetic variation enables broad niche width in a flower living yeast.

by Christina Richards

Schrey, A.W. & C.L. Richards. 2012. Within-genotype epigenetic variation enables broad niche width in a flower living yeast. Molecular Ecology 21: 2559-2561.

Niche theory is one of the central organizing concepts in ecology. Generally, this theory defines a given species... more Niche theory is one of the central organizing concepts in ecology. Generally, this theory defines a given species niche as all of the factors that effect the persistence of the species as well as the impact of the species in a given location. Many studies have argued that phenotypic plasticity enhances niche width because plastic responses allow organisms to express advantageous phenotypes in a broader range of environments. Further, species that exploit habitats with fine-grained variation, or that form metapopulations are expected to develop broad niche widths through phenotypic plasticity. Although a long history of laboratory, greenhouse and reciprocal transplant experiments have provided insight into how plasticity contributes to niche width, recent advances in molecular approaches allow for a mechanistic understanding of plasticity at the molecular level. In particular, variation in epigenetic effects is a potential source of the within-genotype variation that underlies the phenotypic plasticity associated with broad niche widths. Epigenetic mechanisms can alter gene expression and function without altering DNA sequence, and may be stably transmitted across generations. Also, epigenetic mechanisms may be an important component of an individual’s response to the environment. While these ideas are intriguing, few studies have made a clear connection between genome-wide DNA methylation patterns and phenotypic plasticity. In this issue of Molecular Ecology, Herrera et al. (2012) present a study that demonstrates epigenetic changes in genome-wide DNA methylation are causally active in a species’ ability to exploit resources from a broad range of environments and are particularly important in harsh environments.

A Predictive Model to Differentiate the Fruit Bats Cynopterus brachyotis and C. cf. brachyotis Forest (Chiroptera: Pteropodidae) from Malaysia Using Multivariate Analysis. 2012

by M.T. Abdullah, PhD

Read also Abdullah (2003)

Field discrimination of Cynopterus brachyotis and C. cf. brachyotis Forest (as designated by Francis 2008) in southern... more Field discrimination of Cynopterus brachyotis and C. cf. brachyotis Forest (as designated by Francis 2008) in southern Thailand, Peninsular Malaysia, and Borneo is problematic. These 2 forms are sympatric in this region but are confined to different habitat types: C. brachyotis inhabits open habitats, orchards, and agricultural areas, while C. cf. brachyotis Forest is confined to primary and old secondary forests. In this study, we attempted to develop prediction models to identify both C. brachyotis and C. cf. brachyotis Forest in this region based on multivariate statistics. Two predictive models were generated using a canonical discriminant function, and it was found that 5 characters can be used to accurately identify museum vouchers of C. brachyotis and C. cf. brachyotis Forest. Four characters are needed for field identification of these 2 forms of Cynopterus in southern Thailand, Peninsular Malaysia, and Borneo. A review of the current taxonomy and classification indicated that there is a need to describe the 6 existing forms of the C. brachyotis complex in the Indo-Malayan region. This will aid conservationists, field ecologists, and taxonomists in taxonomic- and conservation-related decisions about this species complex.

Molecular phylogenetics and systematics of five genera of Malaysian murine rodents (Maxomys, Sundamys, Leopoldamys, Niviventer and Rattus) inferred from partial mitochondrial cytochrome c oxidase subunit I (COI) gene.

by M.T. Abdullah, PhD

Nur Aida Md Tamrin and M. T. Abdullah. 2011. Journal of Science and Technology in the Tropics 7: 75-86. (SCOPUS-indexed).

We genetically analysed 50 specimens of Murinae from Peninsular Malaysia and Sarawak, assigned to 12 species.... more We genetically analysed 50 specimens of Murinae from Peninsular Malaysia and Sarawak, assigned to 12 species. Phylogenetic analyses of partial mitochondrial cytochrome c oxidase subunit I (476 base pairs) using four methods, namely, neighbour-joining (NJ), maximum parsimony (MP), maximum likelihood (ML) and Bayesian method resulted in similar statistically supported clades with minimal change in branching order. The analyses discovered that there were intermediate form of Maxomys species within M. whiteheadi and M. ochraceiventer populations. They display same external morphology as M. whiteheadi but genetically closer to M. ochraceiventer. Craniodental measurements showed significant differences between the three populations. Rattus and Sundamys appeared not fully resolved while Leopoldamys and Niviventer were steadily clustered. The intraspecific geographic variation in some species agrees with previous studies on the vicariance scenario and diversification of flora and fauna in Malaysia and Borneo.

Nur Aida Md Tamrin and M. T. Abdullah. 2011. Journal of Science and Technology in the Tropics 7: 75-86. (SCOPUS-indexed).

A morphological analysis of Malaysian Kerivoula (Chiroptera, Vespertilionidae).

by M.T. Abdullah, PhD

Related study by Faisal Anwali Khan et al. 2010

Recent identification of new species within the genus Kerivoula from the Southeast Asian region has indicated that... more Recent identification of new species within the genus Kerivoula from the Southeast Asian region has indicated that this genus was understudied and currently underestimated in terms of its species diversity. Thus, this morphological study was carried out to record and analyse the morphological characters of available specimens of Malaysian Kerivoula from the Museum of Zoology, Universiti Malaysia Sarawak. Thirty-one external, skull and dental characters were taken and analysed using the multivariate analysis, dicriminant function analysis. As the result, six groupings of Kerivoula was identified, namely K. intermedia, K. hardwickii, K. pellucida, K. lenis and K. papillosa which were divided into two distinctive groupings of K. papillosa type large (K.
papillosa type L, hereafter) and K. papillosa type small (K. papillosa type S, hereafter). Variable dentary length was identified as the best predictor to characterize each group of Kerivoula. The
separation of the K. papillosa specimens into two separate morphotypes were characterised by their different sizes whereby the former group was larger in size compared to the latter. It is suggested that each represents an independent species even though both morphotypes occur sympatrically. The homogenising effect of the previous environmental events might have been the primary factor of the sympatric occurrence of both morphotypes. Nevertheless, further study regarding ecology, morphology and genetics should be carried out to provide a better insight regarding the cryptic population of K. papillosa in Borneo and Malaysia.

Hasan, N.H., Abdullah, M.T. 2011. Mammal Study 36: 87-97.

Biogeography and variation of the Malaysian fruit bat, Cynopterus brachyotis, in Sunda Shelf 2003

by M.T. Abdullah, PhD

Five more studies by BU, UKM & UNIMAS had tested and confirmed similar findings in this 2003 PhD study.

There are more then one species in the Malayan fruit bat, Cynopterus brachyotis, species complex based on the... more There are more then one species in the Malayan fruit bat, Cynopterus brachyotis, species complex based on the mophological and MtDNA cytochorome b analyses. The small form is found in the closed canopy forest while the larger form utilised the open habitat. There is a new species within the C. brachyotis populations yet to be described.

Ectoparasites of small mammals in Malaysia. 2010

by M.T. Abdullah, PhD

Ixodes granulatus and Leptotrombidium deliense are of known medical importance.

http://www.tm.mahidol.ac.th/seameo/2011-42-4/06-4984.pdf

A total of 16 animals comprising 5 species of hosts were caught and examined for ectoparasites. The hosts examined... more A total of 16 animals comprising 5 species of hosts were caught and examined for ectoparasites. The hosts examined were Maxomys rajah, Maxomys whiteheadi, Leopoldamys sabanus, Lariscus insignis and Tupaia glis. Of these hosts, 9 genera, consisting of 14 species of ectoparasites were extracted. Three species of ticks (Ixodidae), 7 species of mesostigmatid mites (Laelaptidae), 3 species of chiggers (Trombiculidae) and 1 species of listrophorid mites (Listrophoriidae) were identified. The infestation rate of ectoparasites observed ranged from 12.5% to 62.5%. Among the ectoparasites found, Ixodes granulatus and Leptotrombidium deliense are of known medical importance.

Keywords: ectoparasites, small mammals, wildlife reserves, Peninsular Malaysia.

A Madinah, A Fatimah, A Mariana and MT Abdullah

Robotic Lunar Ecopoiesis Test Bed: Bringing the Experimental Method to Terraforming

by Keli Rae

Our publication is in APPENDIX A:  P. J. Boston, P. Todd and K. R. McMillen. Robotic Lunar Ecopoiesis Test Bed: Bringing the
Experimental Method to Terraforming. Space Technology and Applications International Forum -
STAIF 2004, Ed. M. S. El-Genk, American Institute of Physics, Washington, DC, 2004.

The notion of ecologically terraforming another planet (aka ecopoiesis) has been discussed by a number of scholars.... more The notion of ecologically terraforming another planet (aka ecopoiesis) has been discussed by a number of scholars.
Some theoretical treatments of various aspects of ecopoiesis have appeared in the literature. However, experimental
terraforming studies have been rare to non-existent. This is not surprising because of the planetary scale and long durations
typically discussed. We describe a concept to perform basic ecopoietic experiments in a test facility constructed on the lunar
surface. Such a facility can provide long-term observation of organisms and their ecological, physiological, and evolutionary
interactions in a low gravity environment. Salient features of other extraterrestrial environments (e.g. the 0.38g Mars gravity)
can be simulated more easily in the lunar milieu than on Earth while providing much greater access for experimenters than
ecopoiesis experiments on Mars itself. Besides application of these proposed studies to possible future terraforming efforts,
basic evolutionary and ecological processes could be studied under extreme selection pressures including fractional gravity,
high radiation, and with a variety of atmospheres, soils, and other parameters. Novel, genetically engineered and selectively
bred organisms could be tested in such a facility without concern for accidental release into Earth’s environment.

Ecological effects on gut bacterial communities in wild bumble bee colonies.

by Hauke Koch

Koch, H., Cisarovsky, G., Schmid-Hempel, P. (in press) Journal of Animal Ecology

1. Animal hosts harbour diverse and often specific bacterial communities (“microbiota”) in their gut. These microbiota... more 1. Animal hosts harbour diverse and often specific bacterial communities (“microbiota”) in their gut. These microbiota can provide crucial services to the host, such as aiding in digestion of food and immune defence. However, the ecological factors correlating with and eventually shaping these microbiota under natural conditions are poorly understood.
2. Bumble bees have recently been shown to possess simple and highly specific microbiota. We here examine the dynamics of these microbiota in field colonies of the bumble bee Bombus terrestris over one season. The gut bacteria were assessed with culture-independent methods, i.e. with terminal restriction fragment length profiles (TRFLPs) of the 16S rRNA gene.
3. To further understand the factors that affect the microbiota, we experimentally manipulated field-placed colonies in a fully factorial experiment by providing additional food, or by priming the workers’ immune system by injecting heat killed bacteria. We furthermore looked at possible correlates of diversity and composition of the microbiota for a) natural infections with the microbial parasites Crithidia bombi and Nosema bombi; b) bumble bee worker size; c) colony identity, and d) colony age.
4. We found an increase in diversity of the microbiota in individuals naturally infected with either C. bombi or N. bombi. C. bombi infections, however, appear to be only indirectly linked with higher microbial diversity when comparing colonies. The treatments of priming the immune system with heat-killed bacteria, and additional food supply, as well as host body size had no effect on the diversity or composition of the microbiota. Host colony identity had only a weak effect on the composition of the microbiota at the level of resolution of our method. We found both significant increases and decreases in the relative abundance of selected bacterial taxa over the season.
5. We present the first study on the ecological dynamics of gut microbiota in bumble bees and identify parasite infections, colony identity and colony age as important factors influencing the diversity and composition of the bacterial communities. The
absence of an effect of our otherwise effective experimental treatments suggests a remarkable ability of the host to maintain a homeostasis in this community under widely different environments.

Effects of herkogamy and inbreeding on the mating system of Mimulus luteus in the absence of pollinators

by Rodrigo Medel

Self-pollination mechanisms are often invoked to explain plant reproduction in environments devoid of pollinators.... more Self-pollination mechanisms are often invoked to explain plant reproduction in environments devoid of pollinators. However, populations may evolve a diverse variety of strategies depending on the ecological context of pollination. In this study we examined the pollination environment, inbreeding depression, and herkogamy of Mimulus lutes (Phrymaceae) in two consecutive years in an attempt to evaluate the extent to which these factors determine the current level of autogamy in this population. Results indicate that pollinators were almost absent in the study site in 2005 and 2006. Likewise, no evidence of significant inbreeding depression for seed production and seed germination was detected in the 2 years. Because M. luteus presents hermaphrodite flowers with ‘movement herkogamy’ (touch-sensitive stigmata that close upon contact), and anther–stigma separation, we evaluated the role of these traits in self-fertilization. First, we assessed the effects of pollen source (self- and xenogamous pollen, and control solution) on stigmata dynamics after pollen deposition, and seed production. We observed that stigmata that received pollen (self- and xenogamous hand-pollinated) remained closed for a longer time than flowers that received no pollen (control flowers). Seed production, however, was unaffected by pollen
source, indicating that movement herkogamy does not prevent self-fertilization in this population. Second, a phenotypic selection analysis revealed that seed production increased with a reduction of anther–stigma separation in absence of pollinators (bagged flowers), suggesting that low herkogamy levels are promoted in this population. Our results indicate that lack of inbreeding depression, ineffective movement herkogamy, and selection against anther–stigma separation are factors that may contribute to the prevalence of autogamous reproductive mechanisms when M. luteus faces environments with scarce mating opportunity.

Population growth, carrying capacity, and conflict

by Dwight Read

Co-authored with Steven A. LeBlanc. Published in Current Anthropology, 44(1), 2003, pp. 59-85

The standard model of population growth and regulation is critiqued.
It is argued that any model of population... more The standard model of population growth and regulation is critiqued.
It is argued that any model of population growth and regulation
must accommodate ten propositions, and a multitrajectory
model that does so is described. This model identifies
competition between groups, individual choice in reproductive
behavior, the scale for spatial and temporal variation in resource
abundance, and the social unit for resource access and ownership
as important components of population behavior.

An interaction model for resource implement complexity based on risk and number of annual moves

by Dwight Read

Published in American Antiquity 73(4), 2008, pp. 599-625

Different hypotheses identifying factors affecting the complexity of implements used to obtain food resources by... more Different hypotheses identifying factors affecting the complexity of implements used to obtain food resources by huntergatherer
groups are assessed with regression analysis. A regression model based on interaction between growing season as
a proxy measure for risk and number of yearly moves fits data on the complexity of implements for 20 hunter-gatherer
groups. The interaction model leads to a division of hunter-gatherer groups into two subgroups that correspond to collector
vs. forager strategies for procuring resources. Implications of the interaction model for the evolution of complex implements
are discussed.

Sexual size dimorphism and food requirements of nestling birds

by Juan Martínez-Gómez

Canadian Journal of Zoology 71: 2541-2545. 1993.

The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio,... more The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio, according to current sex allocation theory. We studied food requirements of nestling American kestrels (Falco sparverius), a moderately size-dimorphic falcon, by hand-feeding 61 birds from hatching to fledging. Daughters, the larger gender, consumed 6.99% more food than did sons. Sons did not have higher energy expenditure from higher effort during sibling competition than daughters did, so parents must supply more food to satisfy daughters' needs than to satisfy sons'. A review of all related studies shows a strong positive association between the degree of sexual size dimorphism and gender difference in food requirements.

Prey Size Influences Female Competitive Dominance in Nestling American Kestrels (Falco Sparverius)

by Juan Martínez-Gómez

Ecology 74: 367-376. 1993.

Body size differences typically influence sibling competition among nestling birds. In many species hatching order... more Body size differences typically influence sibling competition among nestling birds. In many species hatching order determine nestling size rank; however, sexually dimorphic growth may confound this correlation, giving one sex a consistent competitive advantage and leading to differential survival of the sexes. We found that captive female American Kestrel (Falco sparverius) nestlings were larger than male sibling nestmates from shortly after hatchling through fledging. When food delivered by parents was small enough to be seized and swallowed immediately by a nestling, females showed clear competitive superiority over male sibling nestmates in scramble competition. Females also took larger portions than males of small, yet unmonopolizeable, items. Competitive ability and gender were unrelated when parents delivered large, unmonopolizeable prey. Choice experiments demonstrated that parent feeding preferences did not account for the females' advantage. Based on the above, we expected fledging sex ratio to become increasingly female biased as nestling mortality increased, because nestling mortality increases and prey size decreases when preferred prey (unmonopolizeable rodents) are not available. Data from a wild kestrel population in eastern Pennsylvania supported this prediction, showing a significant positive relationship between fledging brood size and representation of males in the brood, although we note an alternative explanation for this result. Female competitive dominance and its interaction with prey size may influence the evolution of sexual size dimorphism and primary sex ratio in this species and other raptors.

Comments on ‘Weak population differentiation in northern European populations of the endangered anadromous clupeid Alosa fallax'

by Daniel Hasselman

Hasselman, D.J. 2008.  Comments on ‘Weak population differentiation in northern European populations of the endangered anadromous clupeid Alosa fallax.’  Journal of Fish Biology 73: 1096-1098.

Darwin´s pigeons and the evolution of columbiforms: recapitulation of ancient genes

by Juan Martínez-Gómez

Acta Zoológica Mexicana (n.s.) 25(3): 719-741.  2009.

To commemorate the sesquicentennial of Charles Darwin´s “On the Origin of Species by Means of Natural Selection”, we... more To commemorate the sesquicentennial of Charles Darwin´s “On the Origin of Species by Means of Natural Selection”, we address an essential topic in this publication. Domestic pigeons were extremely important in shaping Darwin’s theory of evolution: pigeons featured prominently not only in his “Origin of Species”, but also in his treatise on “Variation under Domestication”, in his “Descent of Man” and finally in his “Expression of Emotions”. Darwin saw the process of domestication as solid evidence demonstrating the power of selection. He argued convincingly that all domestic pigeon breeds (some 150 in his day) descended from one ancestral species, the Rock Dove (Columba livia), and that from this single species, humans selected directionally for colors, sizes, shapes, peculiarities of bill shape and length, plumage characteristics and voice qualities. While these domestic races achieved remarkable morphological differentiation under selection in the course of human generations, extant genera of pigeons (Columbiformes) have attained similar traits during the course of natural selection in the wild. We present a comparison of such characters between modern domestic breeds of the Rock Dove, the original Darwin´s Pigeons plus new breeds, and wild pigeon species to encourage further studies on their evolution in the light of molecular techniques not available at Darwin´s time.

The effects of resource depression on foraging efficiency, diet breadth, and patch use in southern New Zealand

by Lisa Nagaoka

2002, Journal of Anthropological Archaeology

While many studies have examined human impacts on prehistoric environments, few have explicitly examined how foragers... more While many studies have examined human impacts on prehistoric environments, few have explicitly examined how foragers adapt to the changing environmental situations that they have created. The goal of this analysis is to study the relationship between human foraging economies and human-related environmental change in southern New Zealand. Foraging theory is used to generate predictions about subsistence change resulting from the declining abundance of important resources such as moas and seals. In particular, these predictions examine changes in (1) the kind of resources exploited (foraging efficiency), (2) the number of resources utilized (diet breadth), and (3) the habitats exploited (patch choice). The predictions are tested using the large assemblage of vertebrate faunal remains from the well-stratified and well-dated Shag River Mouth site. This study shows that using foraging theory models to structure analysis provides a more fine-grained spatial and temporal resolution of subsistence change in southern New Zealand than has been previously achieved.

Bet-hedging strategies, agricultural change, and unpredictable environments: historical development of dryland agriculture in Kona, Hawaii

by Melinda Allen

MHC genotype and male ornamentation: genetic evidence for the Hamilton-Zuk model

by Mats Grahn