Plant introductions, hybridization and gene flow

Abstract

Many regional floras contain a high proportion of recently introduced plant species. Occasionally, hybridization between an introduced species and another species (introduced or native) can result in interspecific gene flow. This may occur even in instances where the F 1 hybrid shows very high sterility, but occasionally produces a few viable gametes. We provide examples of gene flow occurring between some rhododendrons recently introduced to the British flora, and between an introduced and native Senecio species. Neutral molecular markers have normally been employed to obtain evidence of interspecific gene flow, but the challenge now is to isolate and characterize functional introgressed genes and to determine how they affect the fitness of introgressants and whether they improve adaptation to novel habitats allowing introgressants to expand the range of a species. We outline a candidate gene approach for isolating and characterizing an allele of the RAY gene in Senecio vulgaris, which is believed to have introgressed from S. squalidus, and which causes the production of ray florets in flower heads. We discuss the effects of this introgressed allele on individual fitness, including those that originate directly from the production of ray florets plus those that may arise from pleiotropy and/or linkage.

Towards a unified science of cultural evolution

“…However, we reiterate the point we made in section 2.1.2, that biologists face the same problem, for example, with horizontal gene transfer in bacteria (Doolittle 1999;Rivera & Lake 2004) and plants (Abbott et al 2003). Although we agree with Borgerhoff Mulder et al that it is vital that the parallels between biological and cultural evolution should not blind researchers to the differences, the significance of horizontal transfer to the two disciplines is a matter of degree, not kind.…”

“…However, as noted by , any putative dichotomy contrasting a "divergent, branching biological evolution" with a "convergent, cross-fertilising cultural evolution" is a distortion of both biology and culture. Significant cross-lineage transfer occurs in biological evolution, especially for microbes (Doolittle 1999;Rivera & Lake 2004) and plants (Abbott et al 2003), whereas the convergent nature of culture is an empirically testable hypothesis rather than a statement of fact. Tackling the issue systematically and quantitatively, Tehrani and Collard (2002) found a greater role for branching "phylogenesis" than convergent "ethnogenesis" in Turkmen textile patterns, and Collard et al (2005) have found that the best available cultural data sets show just as good a fit with a branching phylogenetic model as do biological data sets.…”

Amaranthus hybridus can be pollinated frequently by A. tuberculatus under field conditions

“…Previous reports have shown that although hybrid fertility is greatly reduced backcross progeny can be obtained, with fertility increasing in subsequent generations (Tranel et al, 2002). Moreover, for hybrids to be evolutionary meaningful, they need to show a comparative advantage with respect to the original population (Abbott et al, 2003). The acquisition of herbicide resistance via single gene movement, combinatorial gene action, or other hybrid-related mechanism could provide hybrids with such comparative advantage.…”

Gene–culture coevolution and the nature of human sociality

“…Like biological transmission, culture is transmitted from parents to offspring, and like cultural transmission, which is transmitted horizontally to unrelated individuals, so in microbes and many plant species, genes are regularly transferred across lineage boundaries [6,24,25]. Moreover, anthropologists reconstruct the history of social groups by analysing homologous and analogous cultural traits, much as biologists reconstruct the evolution of species by the analysis of shared characters and homologous DNA [26].…”