Fig - Fig Wasp Natural History

http://129.31.3.171/index.html

750 spp. of fig, most with a single sp. of pollinator!!

Fig - Fig Wasp Model

MVP: ~ 170 fig trees are required to eliminate a gap in flowering among trees - i.e., 99% probability of persistence for 1000 years.

Big-Blue ButterflyAn obligate parasite of ant colonies

Butterfly oviposits on thyme

Caterpillar feeds on thyme

Caterpillar enters Myrmica ant nest

Caterpillar is fed by / feeds on ants

Caterpillar becomes a beautiful butterfly

http://faculty.plattsburgh.edu/thomas.wolosz/metapop.htm

Big-Blue Butterfly

• First started disappearing in the 19th century• Hypotheses

– Over-collecting by insect collectors

– Insecticides

– Fragmentation

– Climate change

– Air pollution

• Rapid decline in the 1950’s, extinct by 1979.

Big-Blue Butterfly

BUTTERFLY THYME

ANT COLONY (Myrmica sabuleti)

SHORT GRASSY FIELDS

GRAZING

RABBITSMYXOMATOSIS

Migratory Birds

• Studies have identified a decrease in U.S. neotropical migrants– Decreasing at the rate of 0.5 to 1.0% per year

• Hypotheses– Deforestation in tropics or breeding ground– Susceptibility to predation or cowbird

parasitism on breeding grounds

Brown-headed cowbird

The Evidence

• Based on taxonomically diverse community in eastern U.S.– Decline of migrants equal to ~ 1% / year.

• Based on wood warblers, vireos, gnatcatchers, kinglets, titmice, chickadees, nuthatches, brown creeper, wrens, bluebirds across U.S.– No decline for migrants

– Recent declines in birds with high susceptibility to predation / cowbird parasitism

Black-Footed FerretThe most endangered mammal in N. America

http://www.ngpc.state.ne.us/wildlife/ferret.html

Inter-relationship of species

“The number of bumblebees in any district depends in a great measure upon the number of field-mice, which destroy their combs and nests”. “[Because] the number of mice is largely dependent, as everyone knows, on the number of cats . . . It is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!” - Charles Darwin, On the Origin of Species

Keystone Species

Photo by James M. Cook

Keystone Species

stronginteractors

weakinteractors

Keystones Dominants

Common Cold

Abundance

Tot

al

Eff

ect

From: Meffe and Carroll

Species with a disproportionate effect on community structure.

Problems with the Keystone Species Concept

• Loosely applied

• Difficult to test

• Questionable application

• Conclusion: Focus on interaction strengths

• Grinnell (1917): where a species lives (habitat)

• Elton (1927): what a species does

• Hutchinson (1950s): combination of all biotic and abiotic requirements of a species: n-dimensional “hyper-volume”

temperatureseed size predator density

abun

danc

eEcological Niche

Competitive Exclusion

• If the niches of two competing species overlap by “too much”, then one tends to replace the other.

• Corollary: Competition drives the evolution of divergent niches or life-history strategies (i.e., respond or perish)

niche niche

abun

danc

e abun

danc

e

Darwin’s Finches:Character Displacement

“The Ghost of Competition / Predation Past”

• What we see today may be the result of competition / predation in the past (i.e., implies evolutionary history).– Consider Pleistocene extinctions

• Conservation Implication: Exotic species may have their most negative effects after invading communities that lack an analogous evolutionary partner