Transcript Homologous Structures Convergent Evolution

Natural Selection,
Evolution & Implications for
the Conservation of Wildlife
Evolution
It’s the process that drives•
•
•
•
•
•
the diversity of reproductive strategies we’ve studied…
the ongoing relationships between predator and prey…
the patterns of wildlife distributions around the globe…
responses to disturbances…
guides the migrants…
as well as the demise of all the species that have become
extinct throughout all of time…
Taxonomy: Birds
Class Aves (birds)
Order Anseriformes (ducks, geese, swans, and relatives)
Order Galliformes (chicken-like birds)
Order Caprimulgiformes (nightbirds)
Order Apodiformes (hummingbirds and swifts)
Order Balaenicipitiformes (shoebill or whale-headed stork)
Order Charadriiformes (shorebirds and relatives)
Order Ciconiiformes (storks and relatives)
Order Coliiformes (mousebirds)
Order Columbiformes (doves and pigeons)
Order Coraciiformes (kingfishers and relatives)
Order Cuculiformes (cuckoos and relatives)
Order Falconiformes (diurnal birds of prey)
Order Galbuliformes
Order Gaviiformes (loons)
Order Gruiformes (coots, cranes, and rails)
Order Mesitornithiformes (mesites)
Order Musophagiformes (turacos)
Order Opisthocomiformes (hoatzin)
Order Passeriformes (perching birds)
Order Pelecaniformes (pelicans, tropicbirds, cormorants, and relatives)
Order Phoenicopteriformes (flamingos)
Order Piciformes (woodpeckers and relatives)
Order Podicipediformes (grebes)
Order Procellariiformes (tube-nosed seabirds)
Order Psittaciformes (parrots)
Order Sphenisciformes (penguins)
Order Strigiformes (owls)
Order Trogoniformes (trogons)
Order Turniciformes (buttonquail)
Order Struthioniformes (cassowaries, emus, kiwis, ostriches, and rheas)
Order Tinamiformes (tinamous)
And even for humans, it drives
whowho
will survive…
…and
will not
And may just influence
what happens next on this graph…
Nothing in biology makes sense
except in the light of evolution”
-Theodosius Dobzhansky
Evolution through natural selection
is the foundation of modern ecology,
biology and medicine.
Theory or Fact?
• In everyday vernacular, a theory is “a guess”.
• As a scientific term, a theory is “a statement of
what are held to be the general laws, principles, or
causes of something known or observed” (OED)
• A scientific theory is testable and can make
verifiable predictions
• In fact, it has been noted that we know more about
the mechanisms of evolution than we do gravity, the
nature of light, sleep, the weather, and something
even more nebulous and stormy… love.
Throughout much of human history,
the dominant perspective (and still is
in some of the less educated parts of
the world… and country), was that
everything was divinely created in its
present form, and that this Creator
also orchestrated their interactions
not unlike a master puppeteer.
Theologist: “ What have you learned
about the mind of God in the
course of your studies of biology?”
J.B.S.Haldane: “ Madame, only
that he had an inordinate fondness
for beetles.”
J.B.S. Haldane
Charles Darwin
(1809-1882)
Published one of the most
influential books ever writtenOn the Origin of Speciesin 1859
2009 marks the 200th anniversary
of his birth and 150th anniversary
of the publication of OtOoS
The Galapagos Islands
What is Natural Selection?
“principle by which each slight variation [of a
trait], if useful, is preserved” – Darwin
Natural Selection
• Individuals within populations are variable for nearly
all traits
• Individuals pass on their genes to offspring
• More offspring are produced than can survive
• Individuals that survive and go on to reproduce (the
most) are those with the varieties (alleles) that best
adapt them to their environment
• Outcome: alleles associated with higher fitness
increase in frequency from one generation to the next
Artificial Selection
Artificial Selection
Natural Selection is also a part of population regulation
•
•
•
•
•
•
•
The reproductive potential
of populations is great, but
populations tend to remain
constant in size, because
populations suffer high
mortality.
Individuals vary within
populations, leading to
differential survival of
individuals.
Traits of individuals are
inherited by their offspring.
The composition of the
population changes by the
elimination of unfit
individuals
•
•
•
Rabbits should cover the
earth, but
they don’t, because
•
many are caught by
predators.
Some rabbits run faster
than others,
and escape from predators
•
and so do their young.
•
Populations of rabbits, as a
whole, tend to run faster
than their predecessors.
•
From Ricklef’s “The Economy of Nature” Second Edition
Important Points
• Weak forces operating over long periods of
time create large and dramatic change.
• Natural selection is the non-random survival
of random variants
• Natural selection- by itself- is not evolution.
It is the mechanism that can lead to evolution.
• Natural selection takes place within a
generation, but evolution takes place across
generations.
Watson & Crick
Mechanism of inheritance
DNA
1953
Gregor Mendel
Contemporary of Darwin
“father of genetics” -1866
Heritable traits & dominance
Peter & Rosemary Grant
Daphne Major
Started research project on Darwin finches in 1973.
Geospiza fortis
Graph showing the distribution of beak depths
for medium ground finches in Year 1
34
la Niña = Drought
el Niño = Rains
Drought (la nina)
Wet (el nino)
Following the drought
In 1975, the rainy season came
and
went
of 1977,
85%
of the
with nary a drop of rain (el
Niño)ground finch
medium
population died.
Year 3 Data
40
Caltrop seeds (Tribulus)
• This demonstrates natural selection, but the story
is not quite over…
• The year of the drought, no young were produced
• After the drought, the 15% that survived
represented birds with larger bills.
• These individuals did breed the following year.
• What do think their offspring looked like?
(Small beaks? Medium beaks? Big beaks?)
• This is evolution.
Other evidence for evolution
•
•
•
•
Common structures (homologous)
Analogous structures (convergent evolution)
DNA Research
Fossil Record
•
•
•
•
Embryonic development
Vestigial Organs & Structures
Imperfections in Structure
Drug-Resistant Bacteria
Homologous Structures
~ common ancestor ~
Homologous Structures
Convergent Evolution
~ Physical adaptations to similar ecological conditions~
Convergent Evolution
DNA
- species that appear to be more
distantly related from their positions
in the fossil record are found to have
correspondingly greater differences in
their DNA than species that appear
more closely related in the fossil record.
Fossils
Conservation Connection
“It is not the strongest of the species that
survives, nor the most intelligent,
but the one most responsive to change.”
–Charles Darwin
Punta Alta
“a perfect catacomb for monsters of extinct races”
We are changing the world faster than species are
able to adapt to these changes.
Humans as an Evolutionary Force
• Human-induced evolution caused by
unnatural selection through harvest of wild
animals (Allendorf, F.W. and J. J. Hard. 2009. PNAS. Vol. 106)
• The nature of fisheries- and farming-induced
evolution (Hutchings, J.A. and D.J. Fraser. 2007.Molecular
Ecology. Vol.17)
• Rapid human-induced evolution of insect–
host associations (Singer, M., C.D. Thomas and C. Parmesan.
1993. Nature. Vol. 366)
• Humans as the World's Greatest
Evolutionary Force (Palumbi, S.R. 2001. Science. Vol. 293)
Evolution Books
~The Old Classics~
Evolution Books
~The New Classics~
“It is a century now since Darwin gave us the
first glimpse of the origin of species. We
know now what was unknown to all the
preceding caravan of generations: that men
are only fellow-voyagers with other creatures
in the odyssey of evolution. This new
knowledge should have given us, by this time,
a sense of kinship with fellow-creatures; a
wish to live and let live; a sense of wonder
over the magnitude and duration of the biotic
enterprise.”
~Aldo Leopold