Children of time: the extended synthesis and major metaphors of evolution

Abstract

ABSTRACT. It is time for an expansion and enrichment of evolutionary theory. The "back to the future" proposal contained herein is based on three postulates: 1) Neo-Darwinism is too impoverished for this task; 2) its predecessor, Darwinism, contained the necessary breadth of vision and metaphor to be the basis for an inclusive and unifying theory of biology; and 3) the necessary framework for this new stage in the evolution of evolutionary theory is largely in place.We make our case through the use of a number of metaphorical dualisms designed to help focus discussions toward a more cooperative and productive approach to the study of living systems. Along the way, we suggest a number of selfinduced paradoxes in neo-Darwinian accounts of evolution that are resolved by our perspective. KEY WORDS. Darwinism; nature of the organism; nature of the conditions; extended synthesis; metaphors; time, sequency; simultaneity; thermodynamics; metabolism; space; information; function; history; complexity; cohesion; compensatory changes; evolutionary transitions; cooperation; division of labor; ecological hierarchy; genealogical hierarchy; selforganization. th century reactions against the "hardened synthesis." We then present new metaphors aimed toward allowing researchers to connect Darwin's view of evolution, proposals from the 1980s and 1990s, and calls for an Extended Synthesis.

Understanding Host-Switching by Ecological Fitting

“…According to the model, large populations can explore host fitness space extensively by accumulating non-optimally adapted phenotypes, which increase the capability of the population to use a larger variety of hosts ( Fig 5 ). A fundamental Darwinian view is that variants well-suited to existing local conditions dominate numerically, but variants with low (non-zero) fitness are more likely to survive changes in those conditions [ 5 , 41 ]. Extinction of an optimal host thus will not necessarily result in extinction of a parasite lineage, even if the parasite is highly specialized on that host ( true specialist of Brooks and McLennan [ 5 ]) or has had no opportunity to interact with other hosts prior to the episode of environmental perturbation ( faux specialist of Brooks and McLennan [ 5 ]).…”

Organismal responses to habitat change: herbivore performance, climate and leaf traits in regenerating tropical dry forests

“…To the extent these hypotheses are correct, the loss of mature forest will likely have negative impacts on these organisms. Alternatively, these organisms may actually have broader physiological tolerances than generally assumed, with some built in capacity to respond to evolutionarily novel conditions (Agosta ; Agosta & Klemens ; Brooks & Agosta ), such as those created by the extensive loss of mature forest. Ultimately, the question is empirical.…”

“…While it may suffer sublethal insults to performance in more marginal habitats, it is persisting. Ultimately, the ability to persist and survive change is the most important determinant of ecological and therefore evolutionary success (Brooks & Agosta ).…”

Multi level ecological fitting: indirect life cycles are not a barrier to host switching and invasion

“…This process of ‘ecological fitting’ produces historically and ecologically complex patterns of association between organisms and the environment, including other organisms (Janzen, , ; Brooks & McLennan, ; Agosta, ; Brooks et al ., , b ; Agosta & Klemens, ; Agosta et al ., ). Ecological fitting is not an endpoint, but rather a fundamental step in the larger, ongoing processes of biological expansion and evolution in response to ever‐changing environments (Hoberg & Brooks, , ; Brooks & Agosta, ). Depending on circumstance, ecological fitting can promote evolutionary stasis if, for example, it leads to multiple interconnected populations experiencing contradictory selective pressures (Janzen, ; Agosta & Klemens, ), or can be a precursor to evolutionary diversity, such as when an ecological host switch leads to evolution in response to the novel host (e.g.…”

“…Adding to the complexity of host–parasite systems, parasites track host resources and not the host species themselves (Janzen, ; Brooks & McLennan, , ; Pearse & Hipp, ; Nyman, ; Barrett & Heil, ). Therefore, they have built‐in capacity to form new associations with novel host species because of phylogenetic conservatism or convergence in host resources, without any immediate role for evolution, using whatever traits (information) they carry at the moment of contact (Brooks & McLennan, ; Agosta, ; Brooks et al ., ; Agosta & Klemens, , ; Agosta et al ., ; Harvey et al ., , ; Brooks & Agosta, ). This is ‘ecological fitting’ ( sensu Janzen, ), which we discuss in more detail below.…”