Introduction to Wildlife & Fisheries Conservation
WFSC 304
Lecture 3: Origins, maintenance and future hope for biodiversity
Evolution of Biological Diversity:
From whence comes the diversity of nature?
Everywhere you look in nature you see a complex array of life, each form more intricate and fascinating than the next, all woven into a tapestry that is at once fierce, unforgiving and cold, and yet economical, complimentary, and nurturing. You can see it even in a jar of pond water. From where does it come?
Ecology, science of: study of the distribution and abundance of organisms
(Adrewartha & Birch)
Evolution, science of: study of the distribution and abundance of organismal form
(DeWitt & Langerhans)
Evolution—distr. & abundance of organismal form
Evolution by natural selection can be ‘axiomatized’ into three necessary and sufficient steps:
1) organisms exibit variations variation
2) variations are heritable heredity
3) variations perform differently fitness
These three premises guarantee evolution
Evolution by nat. selxn. creates adaptation… harmony from tragedy
The tragedy is that beings less suited to the conditions of life perish, or fail to reproduce. What arises however are subsequent generations of better fit organisms that can live in relative harmony with their environment. [
Premises 1&2—Phenotypic variation and heredity
Components of phenotypic variation, including heredity…
recall from intro bio or genetics, VP = VG + VE (see fig 2.8 from Primack)
· VG is genetic influence on phenotypic variation
· VE is environmental influence on phenotypic variation
(Note, for the genetically erudite that VP actually =
VG + VE + VG×E + 2 COVG,E + ε, and VG = VA + VI + VD + VM )
What we get then, from the confluence of all genetic and environmental effects [
is a distribution of phenotypes, z, for a given population:
Frequency(z)
z
Evolution is driven by genetically based fitness differences:
Δz = h2 s
Δz – change in population mean of a trait
h2 – degree of trait similarity among relatives
s – trait difference between reproducers and population at large
Consider a population (pop “A”) with a distribution of trait values…
Frequency Fitness
trait value (z)
Now consider a second population (pop “B”)…
Frequency Fitness
trait value (z)
And the outcome…
Frequency
trait value (z)
As Darwin said, “…[T]here is grandeur in this view of life!”