Ohio University BIOS 2500 Midterm 2 Prep

Biogeography

The study of the distributions of populations, species, and higher taxa, including the causes and consequences of species distributions.

Historical Biogeography

The study of the historical circumstances that contribute to the distributions of taxa.

Ecological Biogeography

The study of the ecological circumstances that contribute to the distributions of taxa.

Species Ranges

define where species can thrive based on environmental conditions and evolutionary history.

Endemic Species

they are restricted to a certain region or locality.

Father of Biogeography

David Wallace

Co-discoverer of Natural Selection

David Wallace (alongside Darwin)

Descent with Modification

Evolutionary theory suggests that new species evolve from ancestors within the same region.

Glyptodonts and Armadillos

large, armored mammals found in South America

Armadillos

lived in the same region as gylptodonts and were their modern descendant

Diprotodon

a large prehistoric relative of the wombat, lived in Australia

Modern Wombats

modern descendants of diprotodon , still inhabit Australia today.

Pattern of Geographic Continuity

Species evolve in the same geographic regions as their ancestors, with adaptations occurring within this area.

Darwin's Logic for Islands

Remote islands typically only have species that are capable of long distance dispersal.

Endemic Species Proportion

This amount on an island is highest when the opportunity for dispersal to the island is low.

Continental Ancestry Marks

Hooks on seeds are an adaptation for dispersal by mammals, yet many seeds on islands lacking mammals have hooks.

Extinction

Loss of species.

Dispersal

On oceanic islands those never connected to the mainland, some kinds of organisms are common (birds, bats, tortoises) and others are rare (salamanders, snakes, lions).

Range Expansion

can leave behind relict populations.

Vicariance

The separation of a continuously distributed ancestral species or group of species into separate parts due to the development of geographical or ecological barriers.

Relict Population

A surviving population from a larger group that once had a wider distribution.

Gondwanaland

Consisted of South America, Africa, Antarctica, Australia, and India, existing ~180 million years ago.

Inner Fish vs. Inner Reptile

We evolved from fish and we do not have an inner reptile in the same way.

Synapsid

a group of animals that includes mammals and their extinct ancestors.

Crown Clade

includes the last common ancestor of a group and all of its living (extant) and extinct descendants.

Stem Clade

includes all extinct lineages more closely related to the crown clade than to any other group, but it excludes the crown group itself.

Middle Ear Bones in Mammals

the malleus, incus, and stapes.

Middle Ear Bones in Reptiles

only one bone in the middle ear, the stapes.

Origin of Extra Bones in Mammal Ears

The malleus and incus in mammals evolved from bones in the reptilian jaw (the articular and quadrate bones).

Origin of Hair in Mammals

Hair likely evolved from sensory structures, specifically sensory bristles or vibrissae (whisker-like structures).

Function of Hair in Mammals

Initially, hair may have served a sensory function, helping mammals detect changes in their environment, before adapting to play roles in insulation and thermoregulation.

Natural Selection

Natural selection explains adaptation without needing a designer.

Blind Watchmaker

Natural selection works without foresight or intention, like a 'blind' process.

Artificial Selection

Human-driven breeding for desired traits.

Darwin's Interest in Pigeons

Pigeons were widely bred and came in many varieties, making them an ideal subject for studying how selective breeding could lead to a wide range of traits in a single species.

Three Steps to Natural Selection

1. Individuals vary in phenotype 2. Some of this phenotypic variation is heritable 3. The variable, heritable traits affect an individual's probability of leaving offspring ('selected' by nature)

Evolution of Populations

Populations evolve.

Industrial Melanism

Before 1850: light form at nearly 100%. Coal pollution darkened the tree trunks and killed the lichens. 1848: 1st dark morph in Manchester, England. Within about 50 years, the dark morph increased to nearly 100%. Clear air legislation passed in 1950. Today: light form > 70%. Outcome of natural selection: genetic composition of the population changes across generations.

Difference Between Artificial and Natural Selection

Artificial: human guided. Natural: environmental pressures guide selection.

Understanding Natural Selection

It involves probabilities because not all individuals will survive and reproduce equally.

Testability of Natural Selection

Yes, it is observable in populations (e.g., Darwin's finches).

Beak Morphology in Darwin's Finches

The primary evolutionary change observed in Darwin's finches was in beak size and shape, linked to the availability of food resources.

Heritability of Beak Depth

Observed by tracking trait inheritance through generations.

Histogram

Frequency or count of occurrences.

Natural Selection and Changing Conditions

Natural selection can favor different traits under changing conditions.

Non-random Natural Selection

Acts on specific traits that enhance survival.

Random Aspects of Natural Selection

Genetic Mutations: Mutations happen randomly. Genetic Drift: In smaller populations, random changes in gene frequency can lead to significant shifts in traits.

Predicting the Future with Natural Selection

No, it can't foresee future environmental changes.

Teleology in Natural Selection

Teleology (purpose-driven evolution) is incorrect; evolution doesn't have goals.

Misconception About Evolution

Fishes wanted to get onto land, so they evolved limbs.

Natural Selection and Perfection

Natural selection works with available variations, not towards perfection.

Stepwise Evolution of the Human Eye

Yes, small improvements over time can lead to complex structures.

Fitness of an Organism

Low fitness as it did not pass on genes.

Natural vs. Sexual Selection in Giraffes

Natural Selection: Evolution of long necks may allow giraffes to reach higher foliage. Sexual Selection: Long necks might provide a competitive advantage in 'necking' fights between males.

Adaptation as a Pattern and Process

Pattern: Refers to observable traits enhancing survival. Process: Refers to evolutionary mechanisms producing these traits over time.

Zonosemata vittigera

Experimental work examining the mimicry hypothesis, where wing patterning and movements deter predators by resembling jumping spiders.

Thamnophis elegans

Terrestrial Garter Snake.

Dipsosaurus dorsalis

Desert Iguana.

Megachiropteran Bats

Used to study the evolution of large testes in bats that live in large social groups, examining the correlation with group size and reproductive strategies.

Thermal Performance Curve

A graphical representation showing an organism's performance (e.g., activity, growth rate) across a range of temperatures.

CTmax

The maximum temperature at which an organism can function before physiological processes fail.

CTmin

The minimum temperature at which an organism can function before physiological processes fail.

Independent Contrasts

A statistical method that uses phylogenies to compare evolutionary traits by factoring out shared ancestry, enabling the study of trait correlations.

Phylogenetic Insight

Reveals how certain traits (e.g., bird feathers and hollow bones) might evolve as adaptations to specific environments.

Exaptation

A trait that evolved for one function but was co-opted for another (e.g., bird feathers initially for insulation, later aiding in flight).

Camouflage

A strategy organisms use to blend into their surroundings to avoid detection.

Background Matching

Matching the color or pattern of the background to blend in.

Disruptive Coloration

Using high-contrast patterns to break up body outline, making it harder to detect.

Constructive Relief

Using shadows or textures to blend with physical surroundings.

Masquerade

Mimicking specific objects in the environment (e.g., sticks, leaves).

Differential Blending

Varies colors across the body to match diverse backgrounds, confusing predators.

Maximum Disruptive Contrast

Uses high contrast within patterns to make body outlines difficult to discern.

Eye Stripes

Obscure eye shape or location, making it harder for predators to locate or recognize the organism.

Warning Coloration

Bright colors or patterns that signal to predators the organism is toxic or dangerous.

Mimicry

Organisms mimic other species to gain an advantage.

Batesian Mimicry

Harmless species mimic a harmful one; considered parasitic on the model species (a form of camouflage).

Müllerian Mimicry

Multiple harmful species share similar warning signals, benefiting each other (mutualism).

Correlational Selection

Selection that favors combinations of traits.

Life History

A life history is the schedule and duration of key events in an organism's life, such as growth, reproduction, and death.

Lifetime Reproductive Success

The total number of offspring an organism produces that survive to reproduce themselves.

Trade-off

A trade-off occurs when an increase in one life history trait (e.g., reproduction) leads to a decrease in another (e.g., lifespan or growth).

Ideal organism

An organism that would reproduce immediately after birth, produce infinite offspring, and live forever, but this is biologically impossible.

Allocation

The distribution of an organism's resources (like energy) between different life processes (growth, reproduction, maintenance).

Senescence

The gradual decline in physiological function and reproductive capability with age.

Longevity evolution

Yes, longevity can evolve, especially if there is a genetic basis for traits that contribute to a longer lifespan.

Mutation accumulation hypothesis

Hypothesis that mutations harmful later in life accumulate because natural selection weakens with age.

Antagonistic pleiotropy hypothesis

Hypothesis that some genes have benefits early in life but cause harm later, leading to senescence.

Early reproduction costs

Yes, early reproduction often reduces resources available for later-life survival and future reproductive events.

Mainland/island comparison of senescence

Island opossums tend to live longer and show slower senescence compared to mainland opossums, possibly due to fewer predators.

Offspring size and number trade-off

There is often a trade-off between producing many small offspring and fewer larger offspring due to resource limitations.

Impact of hatcheries on egg size

Hatcheries tend to favor smaller eggs in natural populations, which may reduce survival rates in the wild.

Sexual dimorphism

Differences in appearance between males and females of the same species, often due to sexual selection.

Natural selection vs. sexual selection

Natural selection: Traits increase survival and overall fitness. Sexual selection: Traits improve reproductive success, often by attracting mates or winning competition.

Reproductive investment differences

Females generally invest more (e.g., gestation, parental care), while males may invest less, focusing on mating opportunities.

Human egg vs. sperm size

Human eggs are significantly larger than sperm, with sperm being about 1/10,000 the size of an egg.

Reproductive success

The ability to pass on genes by producing offspring that also reproduce.

Reproductive variance between sexes

Males often show higher reproductive variance than females, with some males producing many offspring and others none.

Bateman's gradient

A measure of the relationship between mating success and reproductive success.

Sex subject to strong sexual selection

Members of the sex subject to strong sexual selection will compete for mates.

Sex subject to weak sexual selection

Members of the sex subject to weak sexual selection will be choosy or selective about mates.