UNIT 13 Chapter 50: An Introduction to Ecology & the Biosphere Chapter 51: Behavioral Biology Chapter 52: Population Ecology Chapter 53: Community Ecology Chapter 54: Ecosystems Chapter 55: Conservation Biology

Ecology is the scientific study of the interactions between organisms and their environment Introduction

Ecologists make predictions of what should be observed in the environment Environment of any organism includes the following components: – Abiotic factors: non-living chemical and physical factors (temperature, light, water, and nutrients) – Biotic factors: the living components

Organismal: behavioral and physiological ways individuals interact with the environment Levels of Ecology

Population: a population is a group of individuals of the same species living in a particular geographic area – Population ecology examines factors that affect population size and composition

Community: a community consists of all the organisms of all the species that inhabit a particular area – Community ecology examines the interactions between populations predation, competition, and disease

Ecosystem: an ecosystem consists of all the abiotic factors in addition to the entire community of species that exist in a certain area – Ecosystem ecology: energy flow cycling of chemicals

Climate is the prevailing weather conditions in an area – Temperature, water, light, and wind are major components of climate Climate determines the makeup of biomes – Major types of ecosystems Ex. Desert, tundra, tropical rain forest, grassland, etc. Temperature & Water

Annual means for temperature and rainfall are reasonably well correlated with the biomes we find in different regions

The tropics between 23.5° north latitude and 23.5° south latitude experience the least seasonal variation and have the highest biodiversity END

Introduction  Ethology is the study of how animals behave in their natural environment  Behavior results from both genes and environment Innate behaviors are fixed, the result of genetics

Learning  Learning is based on experience and results in modification of behavior Maturation: changes resulting from growth and development Habituation: desensitization to unimportant stimulus

 Imprinting is a short period of learning early in life Usually involves young recognizing (and becoming attached to) parents Konrad Lorenz experimented with geese

 Classical conditioning is a type of associative learning Animals learn to associate one stimulus with another  Ivan Pavlov experimented with dogs Ring bell and spray powdered meat in their mouths caused salivation Eventually, the bell alone caused salivation  Operant conditioning involves trial and error Association with a punishment or reward

Cognition  Cognition is the ability to perceive, store, process and use information from sensory receptors Kinesis: change in activity based on random behavior Taxis: movement/orientation based on a stimulus Migration: long-distance movements that occur regularly

Organism Interactions  Social behavior is any interaction between animals (usually the same species) Agonistic: conflict, usually no harm done Dominance hierarchies: involve ranking of individuals  Alpha organism dominates group

 Courtship consists of behaviors that lead to copulation Monogamous – strong bond between male and female Polygamous – multiple mates exist  Polyandry – female with multiple males  Polygyny – male with multiple females Promiscuous – no lasting bond between males and females

Inclusive Fitness  Most social behaviors are selfish, but some involve helping others Altruism decreases individual fitness, but increases fitness of group

 Related individuals will often help each other survive and/or reproduce Kin selection: individuals help relatives raise young END

Introduction  A population is a group of the same species that inhabit the same general area  Density and distribution are influenced by organisms’ interactions with the environment

Survivorship Curves  Demography is the study of the factors that control the growth and decline of populations – Survivorship curves reflect births and deaths in a population  Curve types: Type I, Type II, Type III

Population Growth  The exponential model reflects unlimited resources for growth  The logistic model incorporates limiting factors into population growth – N is the number of individuals – Carrying capacity (K) is the maximum number of individuals that can be supported naturally

 Two basic types of species exist based on reproductive traits – K selection  organisms live/reproduce around K –Long maturation, long lifespan, low deathrate, few offspring, several reproductions in life – r selection  populations fluctuate well below K –Short maturation, short lifespan, high deathrate, many offspring, one reproduction

 Limiting factors fall into two categories – Density dependent  factors increase their pressure as population grows  type of negative feedback – Density independent  factors unrelated to population size, no feedback  Negative feedback prevents unlimited population growth

 Some populations go through regular “boom and bust” cycles – Common with predator/prey interactions

 Age structure is the relative number of individuals at each age END

Introduction A community is a collection of species living closely enough for potential interaction Interspecific interactions involve relationships between species

An organism’s niche is its biotic and abiotic requirements from its environment Its role in the environment Organisms with identical niches cannot coexist (competitive exclusion principle)

Interspecific Interactions Competition, mutualism, commensalism and predation (parasitism) are examples of interspecific interactions Predator/prey interactions have “forced” evolution to develop ways to protect prey species from their predators Coloring, camouflage, toxins, mechanical defenses, etc. Herbivory is a type of predation

Coloration and camouflage are frequently used by nature to aid prey avoid being eaten Cryptic coloration – traditional camouflage, deceptive markings Aposematic coloration – warning colors to indicate the presence of a toxin Batesian mimicry – a harmless species resembles a harmful one Müllerian mimicry – two (or more) “dangerous” species have evolved to resemble one another

Trophic Structure Food chains and food webs are used to trace the path of energy- containing carbon compounds

Disturbance & Succession Disturbances affect community structure and stability Stability is the ability of a community to persist Events like fire, weather, natural disasters and human activity can disturb a community Some events are routine, while others occur randomly Usually considered to have a negative impact, but actually necessary for development and survival

Humans are the most widespread source of disturbance and it usually results in a decrease in species diversity Succession is the sequence of changes that occur after a disturbance Primary succession – occur in a lifeless area Soil needs to be created first by mosses and lichens Secondary succession – occur when an area is cleared by an event Soil still exists, grasses and small shrubs grow END

Trophic Relationships Trophic relationships involve the cycling of carbon in an ecosystem Primary producers are photosynthetic All consumers depend on photosynthetic output

Amount of light energy converted to chemical energy in a given time period is called primary production Ecosystems vary in their productivity Primary Production

Amount of chemical energy converted into a consumer’s biomass is secondary production Secondary Production Joules (J) are unit of energy

Trophic efficiency is typically ~10% Amount of energy passed to next trophic level

Trophic efficiency has important implications for humans

Elements are constantly recycled through ecosystems Carbon cycle Biogeochemical Cycling

Human activity disrupts biogeochemical cycles Nutrients removed from one part of biosphere and placed in another Human Impact Agriculture and eutrophication

Acid precipitation threatens plants and aquatic organisms Caused by burning fossil fuels

Toxins introduced into a food web become more concentrated in successive trophic levels Biological magnification

Human activities were depleting atmospheric ozone (O 3 ) Ozone protects Earth from UV radiation Use of CFC’s is likely cause

Climate change occurs due to rising CO 2 levels in the atmosphere Greenhouse effect causes global warming END