Month: September 2022

FRAGMENT FROM NATURE for this and next weekend focuses on the vexing issue of hybrids, starting with a case study of hybrid rhododendrons, and then to animal hybrids. The transition into a species for a population, which is generally unable to breed with organisms outside that species, is a central tenet of evolutionary theory. But the case study shows that this assignment can be more difficult than it seems. View in LinkedIn

SONG OF DARWIN. "The more I study nature, the more I become impressed […] that the contrivances and beautiful adaptations [acquired through natural selection] transcend in an incomparable degree [those] which the most fertile imagination of the most imaginative man could suggest with unlimited time at his disposal." https://lnkd.in/eykUy37 View in LinkedIn

WIDESPREAD PLANT HYBRIDIZATION. "The occurrence of hybrids, here meaning offspring resulting from two genetically distinct groups of organisms, has been known to taxonomists for a long time. Despite ongoing debate about the overall evolutionary importance of hybridization, the process has been shown to be widespread and relatively common in plants, occurring across many different families and floras." https://lnkd.in/dK-A3iM View in LinkedIn

MISTAKEN SPECIES. "Hybridization has become a focal topic in evolutionary biology, and many taxonomists are aware that the process occurs more frequently than previously assumed. Nonetheless many species and varieties are still described without explicitly considering the possibility of hybridization, especially in countries that have relatively short scientific histories, but which often possess the highest species diversities." https://lnkd.in/dK-A3iM View in LinkedIn

TAXONOMIC ERRORS. "New taxa are often described based only on herbarium specimens, not taking into account information from wild populations, significantly decreasing the potential to detect morphologies arising from hybridization at this crucial descriptive stage." https://lnkd.in/dK-A3iM View in LinkedIn

HYBRID SWARMS IN RHODODENDRON. "We used morphological data from a hybrid swarm involving two Rhododendron species to showcase possible character combinations in intermediates." https://lnkd.in/dK-A3iM View in LinkedIn

MISNAMED PLANT SPECIES. "Despite ongoing debate about the overall evolutionary importance of hybridization, the process has been shown to be widespread and relatively common in plants, occurring across many different families and floras. Indeed, Rieseberg (1997) suggested that a worldwide average of 11 % of all described plant species may be hybrids, and that this figure may even be an underestimate." https://lnkd.in/dK-A3iM View in LinkedIn

REPRODUCTIVE ISOLATION IS KEY. "Regarding description of hybrids as species, an important distinction should be made between reproductively isolated taxa that originated through hybrid speciation (hybrid species) and continuously re-formed hybrids that have distinct features but do not represent a reproductively isolated lineage." https://lnkd.in/dK-A3iM View in LinkedIn

SPECIES NAMING REVERSALS. "Over time there have been many examples across different genera and families, where a plant described as a new species has been subsequently proven to be a hybrid." https://lnkd.in/dK-A3iM View in LinkedIn

UNEVEN PLANT HYBRIDIZATION. "There is strong evidence that hybridization does not occur uniformly across all plant families, and hence spontaneous hybridization seems to be more prevalent in certain families and genera. A group with high levels of natural hybridization is Rhododendron. The genus has more than 1000 species, many of which are interfertile." https://lnkd.in/dK-A3iM View in LinkedIn