A Critical Review of “Dynamics And Viability Of A Metapopulation of the Endangered Iberian Lynx (Lynx pardinus)”
Pilar Gaona, Pablo Ferrerras, and Miguel Delibes
November 1, 2014
In the research under consideration, researchers applied metapopulation models to the endangered Iberian lynx (Lynx pardinus) populations of the Donana National Park in the Iberian peninsula of Spain. In this brief critical review, I will give an overview of what is being doneas well as actions I feel should be considered to save this majestic animal.
The Iberian lynx is a feline that inhabits the Iberian peninsula of Spain. Considered a separate species from the Eurasian lynx, the Iberian lynx finds itself with the unenviable title of being the most endangered felid in the world. The single greatest cause to their precarious status is the human fragmentation of their habitat. Not only is the Iberian lynx separated from the rest of the European lynx population, they are separated from each other into these small pockets of breeding populations, called metapopulations.
Typically the notion of a metapopulation has been one superimposed on the natural world in order to create some parameters of study. In the “real world” only island populations of species have truly exemplified a natural metapopulation model. But with the degradation and fragmentation of contiguous habitat, using metapopulation models is becoming a more reliable and accurate approach, due- regrettably- to the increasing isolation of breeding populations. As conservation moves into the future, metapopulation models will likely become increasingly usable as “useful guides for theory and sound basis for conservation of charismatic endangered species, provided they are well studied in the field.” as the authors succinctly state it.
While this is true, it must be kept in mind that we are still dealing with false stochastic parameters- a needful thing for study- but artificial none the less. Also, there are many variables, such as habitat quality and population genetic bottlenecks that were not taken into consideration in this study.
The good news, overall, is that births will exceed deaths in Donana National Park. But this good news is dampened by the knowledge that the population growth is limited by the availability of good habitat. According to the surveys done for this study, all available breeding territories for females are full. Therefore, there will be no real growth in population without an increase in suitable habitat.
This leads me to one of my critiques of the paper. We know that the Canada lynx population is dependent on the snowshoe hare, and that the snowshoe hare population is in a 7 to 10 year cycle of boom and bust. Shortly after the hare population crescendos the lynx population crescendos. There is also a dramatic drop in the lynx population following the cyclic drop in the hare populations. This is typically a seven year cycle with the Canada lynx as well as this graph from a LynxProject website conveys (http://www.ualberta.ca/~gyates/projectlynx/lynxecology.html)
. Since rabbit is a primary diet for the Iberian lynx as well, it would be interesting to know it there is a similar cycle in the rabbit/lynx population on the Iberian peninsula as well. As coincidence would have it, the two population surveys done in the DNP were seven years apart (1986 and 1992). If such a cycle exists there, could they have accidentally measured at the same point in the cycle? If so, is this the peak of carrying capacity? The bottom of the cycle? These are questions I would want answered.
The authors shy away from offering a “proposal of action” from their study, but wrap up their discussion with a list of suggestions.
First, They suggest creating breeding corridors between metapopulations. Second, they suggest a strategy of increasing source habitat while trying to reduce mortality in sink habitat. Finally, since not all sinks are bad for source sites, they suggest increasing marginal habitat.
My greatest reservation about the approach of the research under consideration, and in particular the proposed actions, is the assumption that these lynx must a) remain genetically pure and distinct from the mainland population and b) that fragmented habitat is a fact that must be accepted rather than addressed. On the latter point, I know it may seem too optimistic, but we must, in s\the scientific community, begin to cast a more forward vision of connected forest with habitable corridors for genetic transfer of populations.
Touching on the genetic isolation issue, I’d like to offer a reflection based on my personal experience.
After the industrial revolution of the mid 19th century, the newly formed middle class taking on dog breeding as a hobby. In short order many new “designer breeds” were created. The philosophy behind these “closed stud book” breeding programs were based on faulty genetic science and racist notions such as the ones culminated in the Nazi regime. The result with these designer breeds were genetic bottlenecks and ever shallowing isolated gene pool.
I offer this analogy because I think we run the same risk in our conservation efforts, in applying these antiquated notions of racial purity to the animals we manage. The red wolves of the southeast are being sterilized for breeding to coyotes. The Northeastern wolf and the southeastern red wolf used to be conspecific before the fragmentation of their habitat. I am not suggesting we forget that there are certain genetic adaptations to a particular ecoregion. But I am suggesting that mainland European lynx be used judiciously in the regions of Iberia with open male ranges to deepen diversity and genetic health. This would also ensure greater resistance to outbreaks of disease within the population.
In conclusion then, while no paper can be exhaustive in its dealing with the survivability of an endangered species, I feel there are many factors, such as the quantitative cycles of lynx populations and the effects of genetic isolation, that merit greater consideration.
Gaona, P., Ferrerras, P., & Delibes, M. (1998). DYNAMICS AND VIABILITY OF A METAPOPULATION OF THE ENDANGERED IBERIAN LYNX (LYNX PARDINUS). Ecological Monographs , 348-371.