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Final Exam

May 11, 8-11 am.

Caraco and Wolf Packer

Why do humans use spices?

H1: They provide extra calories

But very little amounts are used

H2: They provide rare nutrients

Nutritional analyses say no

H3: They help to preserve food longer

Prediction 1: spices show antimicrobial properties

See also: Srinivasan K.  Food Research International 38 (1): 77-86. 2005

Prediction 2: spice use should be proportional not to availability, but to risk of food spoilage

Spices are more commonly used in hot climates where spoilage is more common.

H3: They help to preserve food longer

Sherman PW , Billing J Source:  BioScience 49: 453-463 1999

Habitat selection, dispersal and territoriality

Spatial distribution of resources: random, clumped, dispersed

Ideal Free Distribution: Individuals should distribute themselves among habitats so that every individual maximizes its net rate of return

Homerange: area which an individual, pair, or group occupies or regularly returns to

Core Area: area of heaviest use, may center on a resource, i.e. nest, water source, food source

Territory: any defended area; area of more or less fixed boundaries from which rival conspecifics are excluded through Aggression (self-preservation, protection of the young, or resource competition)

Lek: a communal mating area in which individuals hold small territories solely for courtship and copulation

Kernel (95 and 50%) 95% Minimum Convex Polygon

Different estimators of home range

Horned lizard home ranges overlap with their food - ant colonies

Dispersal: Ecological process affecting distribution.

leaving an area of birth or activity; largely a short range effort but can also be long range

Genetic perspective - can affect geographic differentiation and variation

Choice:Stay in the safety of home (the tendency for offspring to breed in their natal home range is referred to as philopatry).

or

Disperse and take chances: high mortality but high payoffs.

Juvenile dispersal:

Hatching juveniles or fledglings leave their natal area.

Mostly short range but can be long distance (migratory spp.)

birds - bird banding records have found juveniles settling 1000's of kilometers away from their natal area.

lizards - 1.5 km.

Given the length of a hatchling (2.5 cm), this amounts to approximately 60,000 body lengths

the human equivalent of 120 km traveled in the first week or two of life.

Long range dispersal:

Can occur naturally : e.g. Cattle egrets, rafting, storms

Cattle Egrets - original range in Africa1880 - West Suriname1930 - South America, North America

Long range dispersal:

Unintentional or intentional dispersal by humans.

The Argentine ant

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.01 0.1 1 10 100 1000Distance (km)

C.

The Argentine ant

Introduced (non-native, exotic) - species introduced deliberately or accidentally from somewhere else

Definitions:

Domestic/Feral (released pets, livestock and game animals) - can spread disease, compete with native species

Human commensal or subsidized (out of control natives) - native species that benefit from our land use (disturbance)

Invasive species - species that spread subsequent to establishment usually at some cost.

Invasive Species

Some introduced deliberately:

•naturalization societies

•Shakespeare fans

•game animals

•domestic animals

Some accidental:

•ballasts of ships

•unprocessed wood

•fruit shipments

•by-pass natural barriers

Dispersal:Can have incredible energetic costs.A moving animal may be at great risk of predation.How do you find right habitat?

abiotic cuesconspecific attraction

Outbreeding depression

Why do juveniles of most species tend to disperse despite these costs?

Inbreeding avoidance

Reduce competition with relatives

Colonization of new habitat (ideal free distribution)

Belding’s ground squirrels

Sex-biased dispersal - kin avoidance mechanism

Because dispersal entails costs, both sexes of progeny need not disperse to dramatically lower the probability of inbreeding.

One way to reduce costs of dispersal: hitch a ride!

Dispersal: typically associated with a once in a lifetime event -- movement to a new habitat

Orientation: the use of external cues to move about the environment (visual - landmarks)

Navigation: more involved - need to where you are in addition to a “compass sense” (a sense of the appropriate direction in which to move)

Migration: distinct from dispersal - migratory animals typically move from one geographic region to another,without using the intervening habitat. movements often associated with a particular season, and tied to the reproductive cycle.

Who migrates?

birdsinsects (e.g., Monarch butterflies)mammals (caribou, wildebeests, whales)amphibians (e.g., newts to their natal pond)reptiles (e.g., sea turtles)fish (salmon, eels)

Arctic terns

Monarchs take two generations to complete migration!

Cues used for migration:

Celestial compass (sun and polarized light)StarsGeomagnetic fieldVisual (landmarks, shore lines)Smell?

Cochran et al. 2004 Science

Territoriality:

Defending an area from conspecifics.(territory - an area occupied and defended from competitors)

Costs: time, energy, potentially harm

Benefits: resources (shelter, nest sites, food), access to mates

Alternate strategies: sneakers, satellites.

Yarrow’s spiny lizard

Surgeon fish

Why do territorial holders usually win contests when their territory is challenged?

The “dear enemy effect”

Neighbors may learn to recognize each other and reduce aggression as a response.

- lower costs associated with maintaining territory- gang up on foreign intruders.

Evidence in some birds and ants.