How is it that I’ve never heard this cool phrase before? Well not so cool for the species it applies to but still, someone was having a good brain day when that one was coined. The idea of an extinction vortex has been around for almost 25 years but I’m only just hearing about it now (maybe I was asleep, I mean uh sick, that day in biology class). As the name hints an extinction vortex describes factors affecting declining species that make extinction for that species almost inevitable.
The paper that brought this phenomenon to my attention is eye-catching named “Trapped in the extinction vortex? Strong genetic effects in a declining vertebrate population“, published by researchers at the University of Gothenburg, Sweden. The paper looks at the genetic factors influencing the decline of an endangered shorebird the southern dunlin, specifically the effect of reduction of variation in the species due to inbreeding.
The most significant thing about this paper for lay readers is that the primary contributing factors pushing endangered species toward extinction need to be understood in order to put appropriate counter strategies into place. In this case the effects of inbreeding, likely due to reduced population size, have weakened the species and made it more difficult to produce healthy offspring. Protection of the nests and increasing the available habitat for the species did not significantly impact the species’ steady decline. This implies that conservation minded programs should be aware that once a species is in decline multiple strategies, including reproductive approaches, may be required to halt the decline and bring the species back to a stable population.
With currently over six thousand threatened species recognised this would seem to be an important lesson to learn. If conservation efforts are to succeed then at risk populations must be fully evaluated to determine the approach that has the best chance. As noted by the study authors, genetic damage may be hardest to see (via casual observation) when the effects are most severe: when the damage is such that embryos perish before viable individuals can be born.
I can’t sum up better than the study authors themselves so I’ll let their own words wrap things up:
“We have shown that a declining population of a long-lived, endangered vertebrate suffers from substantial negative genetic effects. Our results highlight that ignoring genetics may underestimate the extinction risk of natural populations and thus lead to inappropriate conservation measures”
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