Karner Blue Conservation Methods: Big changes for a little snowflake

The ‘Karner Blue’ is an endangered butterfly species, native to the Great Lakes region of North America. Over the past three decades, they have received considerable attention by conservationists, and this text seeks to support such work by analyzing the conservation methodology. First, ‘undercrowding’ is described as a potential downside of habitat expansion. Next, to mitigate the impact of extreme weather events, a broader geographic distribution is recommended. And finally, breeding programs are discussed for introducing heat-resistant genes to northern populations.

*Note* This text is an ecological analysis of species, and it does not discuss the rights nor welfare of the individual animals involved. The field of ecology commonly uses value-laden language based on shared assumptions, usually representing human interests. For example, the statement “zoos support the Asian Elephant” abstracts the elephants as an ecological grouping, whose human-prescribed conservation goals do not necessarily align with the desires of the elephants themselves.

Undercrowding:

Habitat expansion is the primary means of restoring Karner Blue populations, however this strategy has the potential to backfire. The reason lies in density-dependent factors of survival. 

Many different factors influence population size, including environmental conditions, interactions with other species, and interactions within the population itself. Often, these factors change with population density, as a higher density of individuals results in more-frequent interactions, and a lower density results in fewer interactions. Usually when discussing these density-dependent factors, people emphasize that high density can reduce survival and reproductive rates, such as from intraspecific competition and disease transfer. But for certain species, the inverse may also be a problem, where low density leads to population decline. (Drake, 2011) These low-density phenomena are referred to as ‘Allee effects’ or ‘undercrowding,’ and they have been found to influence Karner Blue populations. Specifically, low population density reduces the ability of Karner Blues to find a mate during breeding seasons (Schuurman, 2023), and inbreeding is a concern where mates are scarce. 

With the creation of habitat and corridors, there is an expected decrease in population density as the butterflies disperse into surrounding environments. And in the case of captive breeding and release programs, if an insufficient quantity of butterflies is released into a new area, then there will be a low population density. In each of these cases, despite efforts to support the Karner Blue, the new habitat is counterproductive due to undercrowding. Habitat expansion may thus hinder population growth, and should be analyzed critically by population ecologists. To offset these density concerns, ‘captive breeding and release programs’ may be used to supplement wild populations, or habitat expansion may be done piecemeal to accommodate for density rebound.

Geographic Range:

Another potential threat to Karner Blues is their limited geographic distribution. Unlike at smaller geographic scales, where conservationists may aim to increase the density of a population, at larger scales it is often beneficial to maintain distance between populations. Distance helps mitigate the impact of localized influences, such as extreme weather events and disease outbreaks, which can wipe-out entire local populations. This was demonstrated by the dramatic disappearance of Karner Blues from Indiana Dunes: driven by climate change, heat and drought from 2012 to 2014 caused local extirpation, constituting a significant loss to the species. 

Currently, Wisconsin has more Karner Blues than any other state due to local conservation efforts, resulting in a biased distribution across the species’ historic range. (Hess, 2015) In 2015, the Sandhill Wildlife Area alone contained about 58-thousand Karner Blue butterflies, which is about 80% of the state’s total number. (National Park Service, 2018) Because of this large-scale concentration of populations, stochastic events in Wisconsin could wipe out a significant portion of the species. By increasing Karner Blue populations in other states, a lower overall proportion of the species will be impacted by such events.

Climate Adaptation:

In the wake of shifting climate regimes, Karner Blues are increasingly exposed to higher temperatures year-round, possibly necessitating human-accelerated adaptation. In a process called ‘assisted migration,’ conservationists can directly relocate individuals (and even entire populations) to more suitable climate regimes. Alternatively, conservationists can perform ‘genetic rescue’ by selectively breeding for climate-resilient traits. (Schuurman, 2023) For the Karner Blue, genetic rescue would involve supplementing northern populations with genetic material from further south, whose populations are better adapted to hot temperatures. Unfortunately, many southern populations have already been lost, as was the case merely 10 years ago in northern Indiana. If these techniques are ever to be used in the future, they would require an immediate shift in conservation priority to protect the southernmost remaining populations, so as not to lose their heat-resistant genetics. 

The primary focus of the Climate Crisis should be mitigation, but assisted adaptation may be necessary as changes have already occurred with unavoidable consequences. Genetic rescue techniques have not yet been used on Karner Blues, however they could be an important strategy in the near future. Such techniques have been previously rejected by Karner Blue conservationists due to the risk of outbreeding depression, however molecular conservationists advise that inbreeding depression and extirpation of existing populations present a much greater risk. Therefore, there has been increasing discussion of genetic rescue of the Karner Blue (Schuurman, 2023), and genome editing technology may be the most effective way to protect them from Climate Change.