- Slides: 11
The Species Concept in Conservation The species concept of conservation has been questioned because: 1. recent advances in molecular genetics introduce questions. Are wolves in Algonquin Park gray wolves (historical view) or red wolves (recent evidence based on DNA analyses)? If the latter, are we going to protect one or both species? 2. Population biologists question whether the species is the appropriate conservation unit.
3. Some argue that species-based conservation efforts may be misplaced since they are biased in favour of mammals and birds at the expense of other microscopic or unattractive taxa; and that the basis should be ecosystem oriented. 4. Still others suggest conservation of 'endangered phenomena', such as that of migrating populations of monarch butterflies, is necessary.
In the U. S. , these various views came to a head in the debate about protection for the Florida panther. The arguments came down to: 1. Protection of the ecosystem, not the species. Conservation groups were split down the middle, with one group suing the US government to stop a captive breeding program intended to protect the species. They argued that protecting the species and not its habitat was foolish and ineffective. The other side wanted to initiate captive breeding to build the population. The resolution will be presented later as a case study. Both sides, however, did want to protect panthers.
2. Is the Florida panther worthy of protection? Developers argued that the species should be removed from the endangered species list since it was a mongrel population. A female puma (panther) originally from Chile was released in the Everglades during the 1950's after they no longer wanted her at a zoo in New York City. She bred successfully and, because of her distinctive genotypic composition, her genes can be tracked in many of the Florida panthers found today. Since it was then a hybrid species, by the Endangered Species Act criteria at that time, the species should not have been protected.
Counter arguments for protection included: a) subspecies, like the Florida panther, are the genetic stock from which new species are derived a) and thus they deserve protection; b) subspecies are locally-adapted organisms that may a) be distinctive from other subspecies; c) the extremely small existing populations of panthers has resulted in significant inbreeding depression. Thus, rather than lamenting introduction of new alleles into the population that this Chilean puma brought to the Florida panther, it should be applauded for expanding the gene pool.
Largely because of this case, ESA guidelines regarding interbreeding were subsequently withdrawn and not replaced. Canada’s Species at Risk Act (SARA) was given royal assent on December 12, 2002, and was implemented in 2003. Its focus is species-based, with the view that endangered species can be protected only through protection of their habitat. Problem: protection for endangered species is legislated on federally owned and managed lands. Many provinces have joined in this protection on crown lands they own or manage. Protection does not extend into private land holdings.
Canada has also recognized vulnerability of specific sub-species or populations (e. g. St. Lawrence population of Beluga whales).
Biological Species Concepts 1. Historic or Typological View - species viewed as having fixed characters; variation is considered unimportant, unfortunate and unusual. Type specimens define the characteristics. 2. Population or Evolutionary View - rather than focus on the norm, this view considers variation the spice of life. Variation is intrinsic to species and is important since it is the raw material through which natural selection and evolution (speciation) occur. This view accepts geographic variation as important in adaptation and speciation.
Biological Species – a definition A species is a group of actually or potentially interbreeding organisms separated from other such groups. Problems: 1) what if ‘species’ (really populations) are not sympatric and therefore never have chance to test species determination? 2) what about asexual species? 3) what about chronospecies (species change through time, as in sequences in the fossil record)? 4) what about species like bacteria that undergo conjugation or introgression (plants)?
An alternative view is the Phylogenetic Species Concept (PSC) - Classification is based on branching relationships among taxa with respect to shared derived characters rather than on reproduction. - A species is the smallest cluster of organisms sharing common features with recognizable parental stock; - This scheme would recognize subspecies as species; thus this scheme recognizes many more species than those classically accepted. In some cases, species delineations are made primarily on the basis of variation in DNA sequences or allozymes.
A cladogram for the chordates