Bio 1010 Exam 3 Extinction Notes

Science

1. isn’t a body of facts

2. is a system of answering questions using hypotheses

3. is not FULLY objective, that’s not possible

r-selected species

they overcome high mortality rates and thrive in unstable environments through very high reproduction rates and producing an extremely large number of offspring per reproductive episode

Can there be limitless growth? Why? Can there be exponential growth?

No, because carrying capacity puts a limit on how large a population can be. However, in the short term there can be exponential growth of a population.

What are the two types of population curves?

J and S

K-selected species

produce few offspring per reproductive episode but should have a low mortality rate

How many inflection points or “bends” do J-curves have.

J-curves have (1) what that S-curves have two of?

Which species types do J-curves and S-curves correspond to?

J-curves to r-selected species, S-curves to K-selected species

How many inflection points do S-curves have?

S-curves have (2) what?

Habitat Fragmentation

Larger habitats being divided into smaller, separated patches stopping ecosystems previously part of the same habitat from interacting.

Source Population / Habitat

births exceed deaths

Sink Populations / Habitat

deaths exceed births

K varies over time. How does this relate to source and sink habitats?

Source habitats in one generation can become sink habitats in another. Why does this happen?

Metapopulation

group of spatially separated populations of the same species which interact at some level

Ecology’s Primary Rule

We can NEVER do just one thing, even if you think you’re doing just one thing you’re actually doong a bunch of things. Ecological interactions are numerous and complicated

20/20 Hindsight & Ecology Addendum

In regards to ecology, we usually understand the relevant, unintended or unexpected interactions after we’ve seen them play out.

The example of Ecology’s Primary rule we discussed in class

Yellowstone, 1970 full removal of wolves, elk, cottonwood, trout, beavers, wetlands, 1996 addition of wolves, coyotes, foxes

A Priori

in advance of

Extant

still in existence; not extinct

Phenotype

observable traits of an organism

Genotype

genetic makeup of an organism, DNA

Attendent Selection Pressures

factors that reduce reproductive success or survival

What natural selection operates on

entire phenotypes and genotypes, not individual traits

Adaptive

traits useful to survival and reproduction

Maladaptive

traits harmful to survival and reproduction

Neutral

traits irrelevant to survival chance and reproduction

Cope’s Rule

Under STABLE environmental conditions, animals in a population experience directional selection (over a generational time) toward larger size

Cope’s Rule Stipulations

not a law; a tendency in SOME groups, especially MAMMALS, like horses

Non-mammal vertebrate used as an example of Cope’s Rule

Pliosaurs

Example we used of size not being adaptive at some point

Diatryma, big bird

Larger size benefits

Larger size allows for greater success in confrontations with predators and competitors, increases survival and most CRUCIAL reproductive rates

Intraspecific

between individuals of the same species

Interspecific

between individuals of different species

Why doesn’t Cope’s Rule apply to unstable environments?

Larger organisms need more food, under unstable conditions, when PRIMARY PRODUCTIVITY is reduced, food becomes SCARCE

Primary productivity

the rate at which sunlight (or inorganic chemicals) are converted into food, organic compounds, biomass by autotrophs

Food Shortage and 10% Rule

autotroph biomass decreases due to unstable conditions, so heterotroph biomass must decrease because of the 10% rule

10% rule

for an organism to grow to weight 100 pounds, it must eat 1000 pounds of food, also only 10% of energy makes it to the next level, 90% is lost along the way through entropy

Entropy

energy dispersal

Adaptive—>Maladaptive

a trait, like size, that is ? in one environment, such as stable conditions with high primary production rates, becomes ? under new conditions

Saber-toothed morphology

Evolved independently (different species) at least 6, 6, 6, SIX, six, times across vertebrate predators

Some evolutionary traits and patterns persist

dolphins, pliosaurs, both evolved from land mammals toward marine forms, limbs aren’t as useful when under water, they both evolved into organisms that didn’t have them

Evolutionary deja vu

Similar selective pressures in different time periods results in convergent evolution

Convergent

things move towards one point, becoming more similar

Saber = maladaptive, adaptive, or neutral?

hard to judge, there have been many organisms that independently evolve saber-teeth, making it seem adaptive, but they are all extinct today, making it seem maladaptive, lowering the opinion of a trait or species because it’s now extinct doesn’t make sense, there are many factors that could have caused it

Saber-tooth Species Mean

4.66 species, 8.13 million years

Genus Homo mean

numerous species, over 2.3 million years

Smilodon Genus Lifetime

2.5 million years

adj.

no members of a species survive

Extinction

n. death of all individuals of a species; none remain alive ANYWHERE

Extirpation

elimination of all populations of a species in a limited area (Gray Wolves, Yellowstone)

Extinction Causes

can result from increased mortality, a higher death rate

Does higher mortality have to result from mass killing or dying events, like an asteroid?

No, it can be caused by other things, like decreased natality due to factors like long-term climate reversal

Natality

birth rate

Can one factor both increase ? an decrease ?

Mortality, natality, Yes, things like climate change or reversal can, due to organisms not being able to live in the environment, and cause physiological stress reducing birth rates

Single Culprit Causation

The preferred explanation for something, one thing caused an event, like the death of the dinosaurs, what we want, but incredibly unrealistic and unlikely, though exceptions exist

Single Culprit Metaphor

better lends itself to factors or events that increased mortality, like natural disasters, than those decreasing natality, since many factors go into decreasing birth rates

Endemism

Ecological condition where a species is unique to a defined geographic location, and found nowhere else on Earth

Single Cause Doesn’t Happen Exceptions

Endemism, the whole population of species lives on one island, and you

Example of island endemism

Fossa

Single Cause Example

An event capable of killing everything on an island with endemism species would be a ? extinction event.