Evolutionary Inertia Research Articles

Family living among birds

Family cohesion in birds is often explained as a product of limitations on breeding opportunities leading to delayed dispersal among the offspring. Yet, it is not independent reproduction but floating (queuing outside the natal territory for a breeding opportunity) that is the alternative to delaying dispersal. In contrast to a strong phylogenetic bias in cooperative breeding that has been taken to indicate a hard‐wired behaviour maintained by evolutionary inertia, offspring behaviour is plastic and facultative in group living in the short term, indicating that family cohesion is under selection. Non‐breeding offspring could gain inclusive fitness that would promote family cohesion from delaying dispersal and providing alloparental care to subsequent broods to boost group productivity. This holds in particular for offspring hatched from early broods in multi‐brooded species that have the opportunity to gain inclusive fitness from help in rearing siblings hatched from later broods in the same season. Yet, seasonality will circumscribe the potential for alloparenting to be the immediate factor selecting for family cohesion. The option of gaining inclusive fitness from providing alloparental care is not open to the offspring among single‐brooded species until after they have survived a non‐breeding season, rather indicating kin cooperation returning enhanced survival prospects from general group living effects as a more immediate factor selecting for family cohesion. Indeed, a variety of family groups maintained in the absence of alloparental care underlines the capacity of general group living enhancing survival as a primary agent selecting for family cohesion. These seasonal constraints on fitness components selecting for family cohesion may contribute to the large scale geographical pattern with a relative paucity of family cohesions among bird species in the northern hemisphere.

Out of Gondwanaland; the evolutionary history of cooperative breeding and social behaviour among crows, magpies, jays and allies

Cooperative breeding is comparatively rare among birds in the mainly temperate and boreal Northern Hemisphere. Here we test if the distribution of breeding systems reflects a response to latitude by means of a phylogenetic analysis using correlates with geographical range among the corvids (crows, jays, magpies and allied groups). The corvids trace their ancestry to the predominantly cooperative 'Corvida' branch of oscine passerines from the Australo-Papuan region on the ancient Gondwanaland supercontinent, but we could not confirm the ancestral state of the breeding system within the family, while family cohesion may be ancestral. Initial diversification among pair-breeding taxa that are basal in the corvid phylogeny, represented by genera such as Pyrrhocorax and Dendrocitta, indicates that the corvid family in its current form could have evolved from pair-breeding ancestors only after they had escaped the Australo-Papuan shield. Within the family, cooperative breeding (alloparental care/family cohesion) is strongly correlated to latitude and its predominance in species maintaining a southerly distribution indicates a secondary evolution of cooperative breeding in the lineage leading away from the basal corvids. Multiple transitions show plasticity in the breeding system, indicating a response to latitude rather than evolutionary inertia. The evolutionary background to the loss of cooperative breeding among species with a northerly distribution is complex and differs between species, indicating a response to a variety of selection forces. Family cohesion where the offspring provide alloparental care is a main route to cooperatively breeding groups among corvids. Some corvid species lost only alloparental care, while maintaining coherent family groups. Other species lost family cohesion and, as a corollary, they also lost the behaviour where retained offspring provide alloparental care.

Are Chilean coastal forests pre‐Pleistocene relicts? Evidence from foliar physiognomy, palaeoclimate, and phytogeography

AbstractAim We ask whether contemporary forests of the Chilean Coastal Range can be considered to be direct and conservative descendants of pre‐Pleistocene palaeofloras that occurred in southern South America from the Palaeogene to early Neogene periods (65–10 Ma), maintaining foliar physiognomies that do not match their present‐day climate. We also identify the most likely ancestors of present‐day coastal forests.Location Coastal Range of south‐central Chile (33–40° S).Methods We compared leaf morphology between five representative modern floras from mid‐latitude forests of the Chilean Coastal Range, and 14 Palaeogene–early Neogene palaeofloras from southern South America. We also compared the composition of biogeographical elements (defined by the modern distribution of plant genera) between fossil and present‐day assemblages. Palaeoclimatic reconstructions were based on a canonical correspondence analysis between leaf morphology of modern assemblages and eight climatic variables, and tested by a Monte Carlo permutation test. We compared the relative positions of fossil and modern floras on the environmental vector space defined by Canoco, and on axes defined by instrumental and estimated temperature and precipitation data.Results According to foliar characters, Palaeogene palaeofloras were strikingly divergent from present‐day coastal forests of central Chile. In contrast, two extant forest floras of the Chilean Coastal Range have a foliar morphology that resembles some late Eocene to early Miocene mixed palaeofloras, at least 23 Myr older. These two modern sites are representative of an area of the Coastal Range (36–37° S) that has been highlighted for its relictual character. None of the 14 fossil floras corresponded exactly to the modern composition of phytogeographic elements, although correspondence analyses showed that mixed and Neogene subtropical fossil floras were compositionally close to the extant woody floras of coastal forests in central Chile.Main Conclusions Contemporary forests of the Chilean Coastal Range exhibit strong physiognomic resemblance to the mixed palaeofloras from 33°57′ to 41°15′ S, which may be the closest ancestor of the deciduous and endemic‐rich Maulino forest, presently restricted to coastal areas between 36° and 38° S. In turn, the Neogene subtropical palaeoflora that occurred in the Proto‐Andean foothills of central Chile is the likely predecessor of Mediterranean‐type sclerophyllous forests of central Chile (32–33° S). Despite foliar resemblance between the late pre‐Pleistocene and extant forest floras, our palaeoclimatic reconstructions suggest that modern assemblages exist under climatic conditions that do not match their foliar physiognomy. We attribute this convergence in foliar morphology to the ‘evolutionary inertia’ of surviving lineages, favoured by the buffering effect of the coastal environment on climatic variability.

Computing the Human

Researchers in artificial intelligence and robotics often include a timeline stretching into the future in which they predict the convergence between human and artificial intelligence. Ray Kurzweil, for example, predicts that in a mere 100 years humans and intelligent machines will become indistinguishable from one another, both ceasing to have permanent corporeal forms. This article argues that the one thing we can know for sure about the future is that when it arrives, it will be different from what we imagined. The cultural work that predictions like Kurzweil’s perform is less to prognosticate the future than to shape our understanding of what it means to be human in the present. Working from the ‘sense-think-act’ paradigm foundational to work in artificial intelligence and robotics, this article argues that predictions in all three areas (sensing, thinking, acting) feed back to affect how the human is envisioned in the present. The reconfigurations these predictions bring about are to downplay consciousness, embodied cognition, and evolutionary inertia. The article concludes by critically evaluating contemporary resistances to the posthuman, especially in the writings of Rodney Brooks and Francis Fukuyama.

Genetic and morphological variation in four populations of the surf clam Donax serra (Röding) from southern African sandy beaches

The surf clam Donax serra (Bivalvia, Donacidae) dominates sandy-beach communities of two southern African biogeographical regions, a cold (Benguela current) and warm province (Agulhas current). Morphometric and behavioural differences led to a controversial discussion of whether or not populations from the two provinces belong to the same species. Shell size measurements confirmed morphological differences: clams from the cold province were significantly rounder, flatter and less wedge-shaped than clams from the warm province. In this study a genetic approach was used to relate phenotypic differences to genetic variability of four populations of D. serra separated by up to 2500 km of shoreline. Genetic analysis of 22 protein-coding loci was carried out by starch-gel electrophoresis. Populations studied are conspecific (genetic distances range from 0.003 to 0.044) and possess genetic variation (alleles per locus: 1.73–1.91; mean heterozygosity: 18–22%; percentage polymorphism: 45.5–59.1%) in the range of most other marine bivalves, which allows for potential adaptation to environmental changes. Wright’s fixation indices show little to moderate genetic divergence among the subpopulations relative to the limiting amount under complete fixation ( F ST=0.016–0.089), moderate divergence of individuals relative to the total population ( F IS=0.265–0.452), and comparably high divergence of individuals relative to the compound population ( F IT=0.300–0.473). The effective number of individuals exchanged between populations in each generation is high enough (1.44–8.65) to counteract genetic drift. We propose that the observed differences represent phenotypic plasticity enabling this species to inhabit different biogeographic regions. Gene flow, balanced selective pressure and evolutionary inertia are discussed as explanations for similarities of the two outlying populations. The substantial subdivision of the two Namibian populations indicates a potential biotic barrier and requires separate studies of the population dynamics.

Tempo and mode in evolution: phylogenetic inertia, adaptation and comparative methods

Abstract Before the Evolutionary Synthesis, ‘phylogenetic inertia’ was associated with theories of orthogenesis, which claimed that organisms possessed an endogenous perfecting principle. The concept in the modern literature dates to Simpson (1944), who used ‘evolutionary inertia’ as a description of pattern in the fossil record. Wilson (1975) used ‘phylogenetic inertia’ to describe population-level or organismal properties that can affect the course of evolution in response to selection. Many current authors now view phylogenetic inertia as an alternative hypothesis to adaptation by natural selection when attempting to explain interspecific variation, covariation or lack thereof in phenotypic traits. Some phylogenetic comparative methods have been claimed to allow quantification and testing of phylogenetic inertia. Although some existing methods do allow valid tests of whether related species tend to resemble each other, which we term ‘phylogenetic signal’, this is simply pattern recognition and does not imply any underlying process. Moreover, comparative data sets generally do not include information that would allow rigorous inferences concerning causal processes underlying such patterns. The concept of phylogenetic inertia needs to be defined and studied with as much care as ‘adaptation’.

Thermal acclimation and non-shivering thermogenesis in three species of South American rodents: a comparison between arid and mesic habitats

Non-hibernating mammals that live in seasonal and arid environments change their non-shivering thermogenesis (NST) capacity to maintain homeothermy. Metabolic capabilities of animals, such as NST, are considered adaptive plastic traits because they have a broad range of possible phenotypes with different ambient temperatures (i.e. the reaction norm). Consequently, we determined the reaction norm for NST in Octodon degus (Bennett, 1832; mb=189 g) andPhyllotis darwini (Waterhouse, 1837; mb=61 g) from the mesic habitat of central Chile, and inPhyllotis xanthopygus (Waterhouse, 1837; mb=67 g) from the high Andean plains of northern Chile, an arid and seasonal habitat. Octodon degus showed a 22% increase in NST with thermal acclimation, whereas P. xanthopygus showed a 112% increase, and P. darwini showed a 117% increase in NST, being the largest change observed. These results are in agreement with our hypothesis of evolutionary inertia, which states that observed metabolic plasticity in Phyllotis species is consequence of their high Andean origin, in spite of the fact the actual habitat ofP. darwini is the less seasonal central valley of Chile.

Evolutionary stasis, constraint and other terminology describing evolutionary patterns

Current use of terms to describe evolutionary patterns is vague and inconsistent. In this paper, logical definitions of terms that describe specific evolutionary patterns are proposed. Evolutionary inertia is defined in a manner analogous to inertia in physics. A character in a static state of evolutionary inertia represents evolutionary stasis while a character showing consistent directional evolutionary change represents evolutionary thrust. I argue that evolutionary stasis should serve as the null hypothesis in all character evolution studies. Deviations from this null model consistent with alternative hypotheses (e.g. random drift, adaptation) can then give us insight into evolutionary processes. Failure to reject a null hypothesis of evolutionary stasis should not be used as a serious explanation of data. The term evolutionary constraint is appropriate only when a selective advantage for a character state transition is established but this transition is prevented by specific, identified factors. One type of evolutionary constraint discussed is evolutionary momentum. A final pattern of evolutionary change discussed is closely related to evolutionary thrust and is referred to as evolutionary acceleration. I provide examples of how this set of definitions can improve our ability to communicate interpretations of evolutionary patterns.

Evolutionary stasis, constraint and other terminology describing evolutionary patterns

Current use of terms to describe evolutionary patterns is vague and inconsistent. In this paper, logical definitions of terms that describe specific evolutionary patterns are proposed. Evolutionary inertia is defined in a manner analogous to inertia in physics. A character in a static state of evolutionary inertia represents evolutionary stasis while a character showing consistent directional evolutionary change represents evolutionary thrust. I argue that evolutionary stasis should serve as the null hypothesis in all character evolution studies. Deviations from this null model consistent with alternative hypotheses (e.g. random drift, adaptation) can then give us insight into evolutionary processes. Failure to reject a null hypothesis of evolutionary stasis should not be used as a serious explanation of data. The term evolutionary constraint is appropriate only when a selective advantage for a character state transition is established but this transition is prevented by specific, identified factors. One type of evolutionary constraint discussed is evolutionary momentum. A final pattern of evolutionary change discussed is closely related to evolutionary thrust and is referred to as evolutionary acceleration. I provide examples of how this set of definitions can improve our ability to communicate interpretations of evolutionary patterns.

Phenotypic plasticity, genetic similarity and evolutionary inertia in changing environments

Phenotypic plasticity, genetic similarity and evolutionary inertia in changing environments

The evolutionary consequences of niche construction: a theoretical investigation using two‐locus theory

AbstractThis paper addresses the joint evolution of environment‐altering (niche constructing) traits, and traits whose fitness depends on alterable sources of natural selection in environments. We explore the evolutionary consequences of this niche construction using a two‐locus population genetic model. The novel conclusions are that niche construction can (1) cause evolutionary inertia and momentum, (2) lead to the fixation of otherwise deleterious alleles, (3) support stable polymorphisms where none are expected, (4) eliminate what would otherwise be stable polymorphisms, and (5) influence disequilibrium. The results suggest that the changes that organisms bring about in their niche can themselves be an important source of natural selection pressures, and imply that evolution may proceed in cycles of selection and niche construction.

Comparative social ecology of feral dogs and wolves

In this paper we compare some socio-ecological traits of feral dogs and wolves in order to assess the social ecology of feral dogs in terms of its adaptive value in the natural environment, and to evaluate to what extent the domestication process altered the wolf's socio-ecological patterns. Referring to feral dogs as those dogs living in a wild state with no food and shelter intentionally provided by humans, and showing a continuous and strong avoidance of direct human contacts, we review the currently available information on feral dog ecology, and particular reference is made to a 3-year term project on feral dog ecology in Abruzzo, Italy. Through comparison of relevant behavioural and ecological features of both wolves and feral dogs, we hypothesize that some aspects of the feral dogs' ecology, having escaped natural selection pressures, represent primarily expression of “evolutionary inertia” or an epiphenomena of artificial selection. Fitness-related measures of sociality, demography, reproduction, space-use, activity patterns, and feeding ecology in feral dogs tend to support our original hypothesis: feral dogs are not reproductively self-sustaining, suffer from high rates of juvenile mortality, depend indirectly upon humans for food, co-optable individuals, and space, and their demography appears dominated by unpredictable mechanisms. However, further research is needed, especially concerning different ecological conditions and multi-generational time-scales, as well as the role that dominant breed-types and cross-breeding history within feral dog groups might play in the expression of the analyzed socio-ecological features.

Beyond Natural Selection.

Part 1 The conventional theory - it is solved: the neo-Darwinist synthesis variants of the theory the commitment to Darwinism the religious challenge. Part 2 The universe of complexity: limits of reductionism higher laws the new outlook of science modernizing Darwinism. Part 3 The cryptic record: problems of origins the leap into the air between land and ocean. Part 4 Inventive nature: the wonder of life remarkable structures fantastic behaviours intelligent instincts problems of creativity. Part 5 Inconsistent nature: adaptation nonadaptation infertility premature death. Part 6 The question of sex: the role of sex sexual practices why sex? Part 7 Sociality: social animals social insects theory of altruism social specialization. Part 8 Dynamics of evolution: the genetic medley the problem of information attractors in the genome variation the role of chaos feedback summary. Part 9 The power of attractors: coherence of pattern limits of change parallel evolution the meaning of parallelism evolutionary inertia. Part 10 Evolutionary change: speciation molecular change - microevolution structural change - neoteny fixity radiation extinction summary. Part 11 Positive adaptation: the presistence of Lamarckism the responsive genome adaptive variation behavioural adaptation learning instinct. Part 12 Evolution and humanity: becoming human the evolution of intelligence intelligence and brain the mind sociobiology cultural evolution. Part 13 Conclusions and perspectives: the autonomy of the genome the direction of evolution the evolution of evolution the anthropic principle the essence of evolution moral meaning of evolution.

Thermal Biology of Nocturnal Ectotherms: Is Sprint Performance of Geckos Maximal at Low Body Temperatures?

Nocturnal geckos are active with body temperatures Tb that are low and variable relative to those of diurnal lizards. If the physiology of geckos is evolutionarily adapted to these low and variable Tb's, then the physiology of geckos should function best at relatively low and variable temperatures. We tested a specific prediction of this hypothesis by comparing the thermal dependence of sprint speed of nocturnal geckos versus diurnal lizards. In fact, optimal temperatures and performance breadths for sprinting of several geckos (Coleonyx brevis, C. variegatus, Hemidactylus frenatus, H. turcicus, Lepidodactylus lugubris) do not differ substantially from those of diurnal lizards from other families. As a result geckos normally forage at night at Tb that should be suboptimal for sprinting. Potential evolutionary explanations (e.g., evolutionary inertia of thermal physiology, possible selection pressures favoring high optimal temperatures) for the similarity of the thermal dependence of sprinting of geckos an...

Relationships between Local Distribution and Geographic Range of Desert Heteromyid Rodents

The extent to which desert heteromyid rodent species are distributed geographically is negatively correlated with their variability in abundance across sites within local regions. In pairwise comparisons, those species with larger ranges generally had lower coefficients of variation in local density across sites than species with smaller ranges. Computer simulations showed this pattern to be significantly non-random in three of the eight data sets examined (data analyzed from three other studies showed the same pattern at 0.1 < p < 0.2). These results are consistent with the abundance/ distribution theories proposed by Hanski and Brown. The results support a large body of literature suggesting that wide-ranging species may have greater ecological success and more evolutionary inertia than species with more restricted distributions. The results also suggest that the ability of species to occur consistently over space may be only indirectly related to the ability to occur stably over time.