Mimicry: Ecology,evolution, and development

1 IntroductionMimicry occurs when one species (the mimic)evolves to resemble a second species (the model) because of the selective benefits associated with confusing a third species (the receiver).For example,natural selection can favor phenotypic convergence between completely unrelated species when an edible species receives the benefit of reduced predation by resembling an inedible species that predators avoid.     

Ecology and evolution of bacterial microdiversity

Using high resolution molecular fingerprinting techniques like random amplification of polymorphic DNA, repetitive extragenic palindromic PCR and multilocus enzyme electrophoresis, a high bacterial diversity below the species and subspecies level (microdiversity) is revealed. It became apparent that bacteria of a certain species living in close association with different plants either as associated rhizosphere bacteria or as plant pathogens or symbiotic organisms, typically reflect this relationship in their genetic relatedness. The strain composition within a population of soil bacterial species at a given field site, which can be identified by these high resolution fingerprinting techniques, was markedly influenced by soil management and soil features. The observed bacterial microdiversity reflected the conditions of the habitat, which select for better adapted forms. In addition, influences of spatial separation on specific groupings of bacteria were found, which argue for the occurrence of isolated microevolution. In this review, examples are presented of bacterial microdiversity as influenced by different ecological factors, with the main emphasis on bacteria from the natural environment. In addition, information available from some of the first complete genome sequences of bacteria (Helicobacter pylori and Escherichia coli) was used to highlight possible mechanisms of molecular evolution through which mutations are created; these include mutator enzymes. Definitions of bacterial species and subspecies ranks are discussed in the light of detailed information from whole genome typing approaches.     

Ecology and evolution of mammalian biodiversity

Mammals have incredible biological diversity, showing extreme flexibility in eco-morphology, physiology, life history and behaviour across their evolutionary history. Undoubtedly, mammals play an important role in ecosystems by providing essential services such as regulating insect populations, seed dispersal and pollination and act as indicators of general ecosystem health. However, the macroecological and macroevolutionary processes underpinning past and present biodiversity patterns are only beginning to be explored on a global scale. It is also particularly important, in the face of the global extinction crisis, to understand these processes in order to be able to use this knowledge to prevent future biodiversity loss and loss of ecosystem services. Unfortunately, efforts to understand mammalian biodiversity have been hampered by a lack of data. New data compilations on current species' distributions, ecologies and evolutionary histories now allow an integrated approach to understand this biodiversity. We review and synthesize these new studies, exploring the past and present ecology and evolution of mammalian biodiversity, and use these findings to speculate about the mammals of our future.     

Ecology and evolution of plant mating

Plants exhibit complex mating patterns because of their immobility, hermaphroditism and reliance on vectors for pollen transfer. Research on plant mating attempts to determine who mates with whom in plant populations and how and why mating patterns become evolutionarily modified. Most theoretical models of mating-system evolution have focused on the fitness consequences of selling and outcrossing, stimulating considerable empirical work on the ecology and genetics of inbreeding depression. Less attention has been given to how the mechanics of pollen dispersal influence the transmission of self and outcross gametes. Recent work on the relation between pollen dispersal and mating suggests that many features of floral design traditionally interpreted as anti-selling mechanisms may function to reduce the mating costs associated with large floral displays.     

Ecology,evolution and genetics join together on Canada's east coast

The 4th regular meeting of the Canadian Society of Ecology and Evolution was held in conjunction with the 52nd Annual Conference of the Genetics Society of Canada at Dalhousie University, Halifax, from 14 to 17 May 2009.     

Ecology and evolution of Devonian trees in New York,USA

The first trees in New York were Middle Devonian (earliest Givetian) cladoxyls (?Duisbergia and Wattieza), with shallow-rooted manoxylic trunks. Cladoxyl trees in New York thus postdate their latest Emsian evolution in Spitzbergen. Progymnosperm trees (?Svalbardia and Callixylon–Archaeopteris) appeared in New York later (mid-Givetian) than progymnosperm trees from Spitzbergen (early Givetian). Associated paleosols are evidence that Wattieza formed intertidal to estuarine mangal and Callixylon formed dry riparian woodland. Also from paleosols comes evidence that Wattieza and Callixylon required about 350 mm more mean annual precipitation than plants of equivalent stature today, that Wattieza tolerated mean annual temperature 7 °C less than current limits of mangal (20 °C), and Callixylon could tolerate temperatures 14 °C less than modern mangal. Devonian mangal and riparian woodland spread into New York from wetter regions elsewhere during transient paleoclimatic spikes of very high CO₂ (3923 ± 238 ppmv), and subhumid (mean annual precipitation 730 ± 147 mm) conditions, which were more likely extrinsic atmospheric perturbations rather than consequences of tree evolution. For most of the Middle Devonian CO₂ was lower (2263 ± 238 ppmv), and paleoclimate in New York was semiarid (mean annual precipitation 484 ± 147 mm). Such transient perturbations and immigration events may explain the 40 million year gap between the late Emsian (400 Ma) evolution of trees and Famennian (360 Ma) CO₂ drawdown and expansion of ice caps.     

Ecology and evolution of symbiosis in metapopulations

We present a model for symbionts in plant host metapopulation. Symbionts are assumed not only to form a systemic infection throughout the host and pass into the host seeds, but also to reproduce and infect new plants by spores. Thus, we study a metapopulation of qualitatively identical patches coupled through seeds and spores dispersal. Symbionts that are only vertically inherited cannot persist in such a uniform environment if they lower the host's fitness. They have to be beneficial in order to coexist with the host if they are not perfectly transmitted to the seeds; but evolution selects for 100% fidelity of infection inheritance. In this model we want to see how mixed strategies (both vertical and horizontal infection) affect the coexistence of uninfected and infected plants at equilibrium; also, what would evolution do for the host, for the symbionts and for their association. We present a detailed classification of the possible equilibria with examples. The stability of the steady states is rigorously proved for the first time in a metapopulation set-up.     

Ecology and evolution of long-lived semelparous plants

One of the more dramatic life histories in the natural world is that characterized by a single, massive, fatal reproductive episode ('semelparity'). A wealth of increasingly sophisticated theoretical models on differential life history evolution have been produced over the last two decades. In recent years, empirical studies of the ecology of semelparous plants (and their iteroparous relatives) have begun to address many aspects of the biology of these species, and to test the assumptions and predictions of theoretical models. Semelparity in long-lived plants is one of the few natural phenomena that has yielded specific quantitative tests of mathematical evolutionary theory.     

Ecology and evolution of extravagant feather ornaments

The ancestral conditions that permit the evolution of extravagant secondary sexual characters are of considerable theoretical and empirical interest because they allow identification of necessary ecological conditions, but also allow empirical tests of models of female mate preferences. We investigated the ancestral and derived state of a range of ecological and evolutionary variables that might have been implicated in the evolution of secondary sexual characters. Extravagant feather ornaments have evolved independently at least 70 times in birds, and the context of these evolutionary events was investigated statistically. The acquisition of feather ornaments was significantly associated with a change in social mating system from monogamy to polygyny or lekking. This association is consistent with the Fisherian mechanism of sexual selection. However, very often also the acquisition of feather ornaments occurred without change in mating system. Therefore, ornamentation can develop for reasons other than polygyny. We did not find any indication of male parental care, kind of food, foraging mode, coloniality, nest site, migration or body mass being significantly associated with a change in the state of ornamentation.     

Ecology and evolution of symbiosis in metapopulations

We present a model for symbionts in plant host metapopulation. Symbionts are assumed not only to form a systemic infection throughout the host and pass into the host seeds, but also to reproduce and infect new plants by spores. Thus, we study a metapopulation of qualitatively identical patches coupled through seeds and spores dispersal. Symbionts that are only vertically inherited cannot persist in such a uniform environment if they lower the host's fitness. They have to be beneficial in order to coexist with the host if they are not perfectly transmitted to the seeds; but evolution selects for 100% fidelity of infection inheritance. In this model we want to see how mixed strategies (both vertical and horizontal infection) affect the coexistence of uninfected and infected plants at equilibrium; also, what would evolution do for the host, for the symbionts and for their association. We present a detailed classification of the possible equilibria with examples. The stability of the steady states is rigorously proved for the first time in a metapopulation set-up.     

Ecology and evolution join forces to good effect

The 3rd regular meeting of the Canadian Society of Ecology and Evolution was held at the University of British Columbia, Vancouver, Canada from 11 to 14 May 2008.     

Ecology and evolution of Jurassic trigoniid bivalves in Europe

 A modern palaeobiological approach to the taxonomy, making full allowance for a wide range of variation, has allowed the distinction of 22 Jurassic trigoniid species in Europe, grouped into 7 genera. Most species were confined to shallow marine habitats ranging up to a few tens of metres in depth but were adapted to low energy environments as well as environments of moderate to high energy. The presence of external ornament on the shell flanks was probably an adaptation to facilitate burrowing, but in the absence of useful external ornament other adaptations to increase burrowing efficiency may have been realized by the development of an elongate shape. Because their occurrence in Jurassic strata is only intermittent, confident inferences on evolutionary patterns are limited to the two commonest genera, Trigonia and Myophorella. Phyletic size increase has been recognized in the latter but not the former genus. The calculated species longevities correspond fairly closely with those established for Jurassic bivalve species in general. The mode of speciation is dominantly punctuational, but only one likely example of species splitting is recognized.     

Ecology and energetics of encephalization in hominid evolution.

Hominid evolution is marked by very significant increase in relative brain size. Because relative brain size has been linked to energetic requirements it is possible to look at the pattern of encephalization as a factor in the evolution of human foraging and dietary strategies. Major expansion of the brain is associated with Homo rather than the Hominidae as a whole, and the energetic costs are likely to have forced a prolongation of growth rates and secondary altriciality. It is calculated here that modern human infants have energetic requirements approximately 9% greater than similar size apes due to their large brains. Consideration of energetic costs of brain allow the prediction of growth rates in hominid taxa and an examination of the implications for life-history strategy and foraging behaviour.