Chapter 21On the Tracks of Wolves and Moose

Young Gray Wolf-Romeo

• Every summer and a few weeks in winter, scientist investigate the Isle Royale’s pack of wolves and herd of moose

• Studies for almost 50 years, it is the longest-running predator prey study in the world.– Scientists would like to understand the dynamic

fluctuations of the wolves and moose. – They are trying to learn about ecology

Ecology

• Ecology is the study of the interactions between organisms, and between organisms and their nonliving environment (land, water, etc.)– The Isle Royale is a great place to study ecology– Uninhabited by humans, protected national park,

undistributed by hunting, logging, settlement– No other predators or prey on the island– Island just the right size to study ecology

Ecology

• Ecologists can study organisms at a number of levels: the individual, the population, the community, and the ecosystem.

Ecology

• At the individual level, ecologists can study how an individual organisms fares in its surroundings.

Ecology

• At the population level, ecologists study a group of individuals of the same species living and interacting in the same region.

Ecology

• At the community level, ecologists study interacting populations of different species.

Ecology

• At the ecosystem level, ecologists study all the living organisms in an area and the nonliving components of the environment with which they interact.

Ecology

• Ecology is a multidisciplinary science. It draws not only on many areas of biology but also on many other branches of science, including geography and meteorology as well as mathematics.

Distribution patterns

• Moose are relatively solitary creatures– Random dispersion of individual roaming moose

on the island.– Hard to count for research studies. – One type of distribution pattern

Moose

• The distribution pattern, or the way that organisms are distributed in geographic space, depends on resources and interactions with other members of the population.– For moose, being solitary may help protect them

from predation – harder to see in forest– A truly random distribution is rare in nature– Resources may be unevenly distributed, etc.,– Distribution pattern are different for wolves and

moose- wolves clump

Distribution patterns• Distribution patterns generally reflect behavioral or

ecological adaptations. Three different types:

Distribution patterns

• A random distribution may allow individuals to maximize their access to resources.

Distribution patterns

• A clumped distribution may result when resources are unevenly distributed across the landscape, or when social behavior dictates grouping.

Distribution patterns

• Uniform distribution usually results from territorial behavior.

Moose

• Few Moose swam to Isle Royale in 1900• Moose population exploded on the Isle Royale

due to abundant food supply and no natural predators

• By 1920, more than a 1000• Rapid increase in growth rate

Population growth• The growth rate of a population is the difference

between the birth rate and the death rate of a given population.

Population growth• Ecologists describe two general types of population

growth: exponential growth and logistic growth.

Population growth

• Exponential growth is the unrestricted growth of a population increasing at a constant growth rate.

• When a population is growing exponentially, it increases by a certain fixed percentage every generation. Increase 20% each year, for example

Population growth

• Unrestricted growth is rarely, if ever, found unchecked in nature.

• As populations increase in numbers, various environmental factors such as food availability and access to habitat limit an organism’s ability to reproduce.

Population growth• When population-

limiting factors slow the growth rate, the result is logistic growth―a pattern of growth that starts rapidly and then slows.

• Disease, food limitation

Population growth

• Eventually, after a period of rapid growth, the size of the population may level off and stop growing.

• At this point, the population has reached the environment’s carrying capacity ―the maximum number of individuals that an environment can support given its space and resources.

Population growth

• Carrying capacity places an upper limit on the size of any population;

• No natural population can grow exponentially forever without eventually reaching a point at which resource scarcity and other factors limit population growth.

Population growth

• Ecologists use a variety of data to monitor the health of populations.– Moose dropping– Moose bones– Wolf scat– Urine –soaked snow

Population growth

• Population density is the number of organisms per given area. Wolves kill moose– As the population density of a species increases,

individuals of that species may face food shortages. • This is an example of a density-dependent

factor―a factor whose influence on population size and growth depends on the number and crowding of individuals in the population.

Population growth

Biotic refers to the living components of an environment. Not all density-dependent factors are biotic. – Food, predators, diseases

• Nonliving, or abiotic, factors like weather and habitat can also influence population size in a density-dependent manner.

Population growth

• Density-independent factors take a toll on the population no matter how large or small the population is.

• Most, but not all, density-independent factors are abiotic.

Chapter 22What’s Happening to Honey Bees?

Honey Bee’s

• Bee’s help farmer’s pollinate local crops– Almonds to melons

• Colony collapse disorder (CCD)- what happened to the bees?

• Several beekeepers reported 30-90% loss of bee colonies

• Over 3 million honey bees have been wiped out• What is happening to the honey bees????

Bees

• Loss of agricultural crops• Affect on health and diversity of ecosystems

that rely on bees for services• Pollination of flowering plants depends on

insects.- bees– 75% of the 250,000 species of flowering plants

depend on insects– Bees are the most important

Community Ecology

• Bees are keystone species• A keystone species plays a central role in

holding a community together because other species depend on it. The removal of a keystone species has a dramatic impact on the community.

• A community is a group of interacting populations of different species living together in the same area.

Community Ecology

• Bees are a keystone species. Many of the crops that we rely on for food, fuel, and fiber rely on bees for their pollination and reproduction.

Crops

• In US more than 100 different crops relay on honey bee pollination

• 15 billion annually

Flowering Plant Reproduction Relies on Pollinators

• Flowering plants use their flowers and nectar to attract pollinators for pollination – the transfer of pollen (small, thick-walled plant structures that contain cells that will develop into sperm) from male to female plant structures so that fertilization can occur.

Flowering Plant Reproduction Relies on Pollinators

• The male flowering plant reproductive organ, called a stamen, consists of a stem-like filament topped with a pollen-saturated anther.

• When a bee lands on or brushes against an anther during her pursuit of nectar and pollen, her furry body picks up pollen grains.

Flowering Plant Reproduction Relies on Pollinators

• As the bee continues to forage, she carries the pollen to the female reproductive organ of the flower – the pistil.

• The pistil is topped with a sticky “landing pad” called a stigma.

• When a bee lands on the stigma, pollen grains are deposited, and from there travel down a tube-like style into the ovary, where they fertilize the egg.

Flowering Plant Reproduction Relies on Pollinators

• A fertilized egg will eventually develop into an embryo-containing seed, while the surrounding ovary eventually becomes the fruit.

Food Chains

• Keystone species play a crucial role in food chains – the linked sequences of feeding relationships in a community in which organisms further up the chain feed on those below them.

Food Chains

• The base of the food chain is composed of producers – autotrophs that obtain energy directly from the sun and supply it to the rest of the food chain.

Food Chains

• Consumers – heterotrophic organisms that eat the producers or eat other organisms lower on the chain to obtain energy – are found higher on the food chain.

Food Chains

• Predation is an interaction between two organisms in which one organism (the predator) feeds on the other (the prey). Herbivory is predation on plants, which may or may not kill the plant preyed on.

Food Chains

• As consumers prey on organisms below them in the chain, energy is transferred up the chain through what are known as trophic levels (feeding levels, based on positions in a food chain).

Food Chains

• Not all of the energy stored in a lower level makes it to the level above it; at each step, much of this energy is lost from the chain.

• Energy is lost as?? • Only about 10% of the energy at the lower

level is passed from one organism to the next organism in the chain.

Food Webs

• The food-chain concept is an oversimplification.

• Many organisms are omnivores (that is, they eat both plants and animals) and so occupy more than one position in the chain.

• The result is a complex, intertwined food web of feeding relationships in a community.

Symbiotic Relationships

• Parasitism is a type of symbiotic relationship in which one member benefits at the expense of the other.

Symbiotic Relationships

• Mutualism is a type of symbiotic relationship in which both members benefit.

Symbiotic Relationships

• Commensalism is a type of symbiotic relationship in which one member benefits and the other is unharmed.

Competing for Resources• An ecological

niche includes the space, environmental conditions, and resources (including other living species) that a species needs in order to survive and reproduce.

Competing for Resources

• When two or more species rely on the same limited resources – that is, when their niches overlap – the result is competition.

• Competition tends to limit the size of competing populations and may even drive one out.- extinction

Competing for Resources• The competitive

exclusion principle is the concept that when two species compete for resources in an identical niche, one is inevitably driven to extinction.

Competing for Resources

• Very few species share exactly the same niche, so different species may find a competitive balance by resource partitioning.

Humans Impact Other Species

• Human development and agriculture have altered and decreased habitat for other species.

What is killing the honey bees?

• CCD• Pesticides, stress, nutrition, parasites, viruses• Some believe we suffer from NDD or nature

deficit disorder• People need to take more time to understand

where their food comes from.• Haagen-Dazs