Transcript Species Concepts

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
and thus they deserve protection;
b) subspecies are locally-adapted organisms that may
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