English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Background: Speciation corresponds to the progressive establishment ofreproductive barriers between groups of individuals derived from an ancestralstock. Since Darwin did not believe that reproductive barriers could beselected for, he proposed that most events of speciation would occur through aprocess of separation and divergence, and this point of view is still shared bymost evolutionary biologists today. Results: I do, however, contend that, if somuch speciation occurs, the most likely explanation is that there must beconditions where reproductive barriers can be directly selected for. In otherwords, situations where it is advantageous for individuals to reproducepreferentially within a small group and reduce their breeding with the rest ofthe ancestral population. This leads me to propose a model whereby new speciesarise not by populations splitting into separate branches, but by smallinbreeding groups "budding" from an ancestral stock. This would be driven byseveral advantages of inbreeding, and mainly by advantageous recessivephenotypes, which could only be retained in the context of inbreeding.Reproductive barriers would thus not arise as secondary consequences ofdivergent evolution in populations isolated from one another, but under thedirect selective pressure of ancestral stocks. Many documented cases ofspeciation in natural populations appear to fit the model proposed, with morespeciation occurring in populations with high inbreeding coefficients, and manyrecessive characters identified as central to the phenomenon of speciation,with these recessive mutations expected to be surrounded by patterns of limitedgenomic diversity. Conclusions: Whilst adaptive evolution would correspond togains of function that would, most of the time, be dominant, this type ofspeciation by budding would thus be driven by mutations resulting in theadvantageous loss of certain functions since recessive mutations very oftencorrespond to the inactivation of a gene. A very important further advantage ofinbreeding is that it reduces the accumulation of recessive mutations ingenomes. A consequence of the model proposed is that the existence of specieswould correspond to a metastable equilibrium between inbreeding andoutbreeding, with excessive inbreeding promoting speciation, and excessiveoutbreeding resulting in irreversible accumulation of recessive mutations thatcould ultimately only lead to extinction.

The existence of species rests on a metastable equilibrium between  inbreeding and outbreeding. An essay on the close relationship between  speciation, inbreeding and recessive mutations