Ecology Population Ecology Part 2

2 Predicting Populations Sex and the Single Guppy

Natural Selection This includes describing how organisms respond to the environment and how organisms are distributed. – Events that occur in the framework of ecological time (minutes, months, years) translate into effects over the longer scale of evolutionary time (decades, centuries, millennia, and longer). 3

Natural Selection 4

Natural Processes 5

Finch Beak Size or Shape 6

Modes of Selection 7

Modes of Selection Disruptive- produces a bi- modal curve as the extreme traits are favored Stabilizing-reduces variance over time as the traits move closer to the mean Directional-favors a phenotypic trait (selected by the environment)

Scenario 9 These photographs show the same location on Captiva Island following Hurricane Charley. What would happen to a population of birds who derive their diets from the tree tops? The population had a wide range of beak sizes. What would happen to the population gene pool over time if the new environment favored smaller beaks? Over time, which beak would be most represented in the population of birds?

Selection Diagrams 10 ABC

Beak Selection After Hurricane 11

Biogeography & Distribution of Species Serves as a starting point to understanding limits on distribution of species Species absent because Yes No Dispersal limits distribution? Yes No Yes No

Biogeography & Distribution of Species Serves as a starting point to understanding limits on distribution of species Species absent because Yes No Dispersal limits distribution? Behavior limits distribution? Yes No Yes No Area inaccessible or insufficient time

Biogeography & Distribution of Species Serves as a starting point to understanding limits on distribution of species Species absent because Yes No Dispersal limits distribution? Behavior limits distribution? Biotic factors (other species) limit distribution? Yes No Yes No Area inaccessible or insufficient time Habitat selection

Biogeography & Distribution of Species Serves as a starting point to understanding limits on distribution of species Species absent because Yes No Dispersal limits distribution? Behavior limits distribution? Biotic factors (other species) limit distribution? Abiotic factors limit distribution? Yes No Yes No Area inaccessible or insufficient time Habitat selection Predation, parasitism, competition, disease

Biogeography & Distribution of Species Serves as a starting point to understanding limits on distribution of species Species absent because Yes No Dispersal limits distribution? Behavior limits distribution? Biotic factors (other species) limit distribution? Abiotic factors limit distribution? Yes No Yes No Area inaccessible or insufficient time Habitat selection Predation, parasitism, competition, disease Water Oxygen Salinity pH Soil nutrients, etc. Temperature Light Soil structure Fire Moisture, etc. Chemical factors Physical factors

Hydrangea Flower Color Hydrangea react to the environment and ultimately display their phenotype based on the pH of their soil. Hydrangea flower color is affected by light and soil pH. Soil pH exerts the main influence on which color a hydrangea plant will display. 17

Fish And Maintaining Homeostasis In Various Water Conditions 18 Fish and other aquatic animals deal with changing environments in part due to nature and in part due to human interactions. Pressure- their bladder fills with gas to equalize internal pressure

Biogeographic Realms 19

Introduced Species What’s the big deal? These species are free from predators, parasites and pathogens that limit their populations in their native habitats. These transplanted species disrupt their new community by preying on native organisms or outcompeting them for resources. 20

Guam: Brown Tree Snake The brown tree snake was accidentally introduced to Guam as a stowaway in military cargo from other parts of the South Pacific after World War II. Since then, 12 species of birds and 6 species of lizards the snakes ate have become extinct. Guam had no native snakes. 21 Dispersal of Brown Tree Snake

Southern U.S.: Kudzu Vine The Asian plant Kudzu was introduced by the U.S. Dept. of Agriculture with good intentions. It was introduced from Japanese pavilion in the 1876 Centennial Exposition in Philadelphia. It was to help control erosion but has taken over large areas of the landscape in the Southern U.S. 22

Introduced Species 23

New York: European Starling From the New York Times, 1990 The year was 1890 when an eccentric drug manufacturer named Eugene Schieffelin entered New York City's Central Park and released some 60 European starlings he had imported from England. In 1891 he loosed 40 more. Schieffelin's motives were as romantic as they were ill fated: he hoped to introduce into North America every bird mentioned by Shakespeare. Skylarks and song thrushes failed to thrive, but the enormity of his success with starlings continues to haunt us. This centennial year is worth observing as an object lesson in how even noble intentions can lead to disaster when humanity meddles with nature. 24