Ecology

The scientific study of interactions among organisms and between organisms and their

environment.

Ecology

There is a constant flow of energy within an ecosystem.

Organisms are interacting with one another in various ways.

In the following photographs, let’s discuss as a group the interactions we observe amongst the organisms in their environment.

Relationships among organisms







How do plants benefit animals?Examples…

How do animals benefit plants?Examples…


Now we’re going to take a short pre-test to determine what you already know about ecology.

This will benefit you by helping me decide what you need to learn about ecology during this semester.

Pre-Test

Species – group of organisms who have similar anatomical characteristics and who possess the ability to interbreed.

Classification Rules:Species are always designated in Latin in a

genus-species binomial naming systemExample: Homo sapiens, or “wise man” in

Latin. The genus name is written prior to the

species name. The entire name is italicized and the genus name is capitalized.

Levels of Organization

Ecologists study the complexity of organisms and their relationships by level or organization.

The levels are:1. Individuals (of a certain species)2. Populations (of individuals of a certain

species)3. Communities (of different populations in one

area)4. Ecosystems (all organisms in an area +

abiotic factors)5. Biomes (group of ecosystems with same

climate)6. The Biosphere (Earth)


The biosphere contains the combined portions of the planet in which all of life exists, including: landwaterair, or atmosphere

The biosphere extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean.

The Biosphere


Ecologists use three main methods to study ecology:ObservingExperimentingModeling

Observations of organisms and their interactions are used to develop hypotheses and plan experiments.

Experiments are performed to test hypotheses. Some are done in artificial setups while others are conducted in the field.

Modeling is done using mathematical calculations to predict the outcomes of various interactions.

Methods used while studying ecology

Cowbird Parasitism and Increased Predation of Indigo Bunting Nests as a Reflection of Nest Site Selection

Jesse Howell and Sarah L. MartinDepartment of Biology 101 T. H. Morgan BuildingUniversity of Kentucky Lexington, KY 40506-0225

Introduction

Methods

Results ConclusionsBrown-headed cowbirds (Molothrus ater) parasitize other bird species by placing their eggs into the host specie’s nest and requiring the host to care for them. Indigo buntings (Passerina cyanea) are a shrub-nesting passerine known to suffer high rates of parasitism and predation. Nest parasitism and predation are influenced by nest habitat and landscape. Payne and Payne (1998) indicated that increased parasitism can lead to increased rates of predation. Our study’s objective was to link nest site characteristics to rates of parasitism and predation and find a correlation between brood parasitism and increased rates of predation as it corresponds to nest site choice.

We examined nests in Griffith Woods, Harrison County, Kentucky from May – August 2008. We located indigo buntings’ nests by following males from their song perches and observing their mates. Nests were monitored every two days for development. Nest fate was determined to be successful, parasitized, predated, or parasitized and then predated. Nests found empty were assigned an unknown fate and not included in analysis (N = 15). After nests were no longer active, those with a known fate (N = 57) were noted with the following nest site characteristics: field type in which the nest was found, plant species in which they nested, vegetation height, nest cup height, placement of nest within the plant species, stem diameter, distance from nest to nearest edge, type of edge, width of edge, an observer objective nest visibility percentage at 1 m from nest from the four cardinal directions and above the nest, and an observer objective average shrub cover averaged from four quadrants extending from the nest in a 5 m radius

• Of the nests we analyzed, 19 were parasitized only, 18 were predated only, 9 were parasitized and then predated, and 11 fledged successfully.• We found that nest height (F = 3.1, P = 0.035) and percent visibility from above the nest (F = 3.2, P = 0.032) among groups, were both statistically significant factors affecting predation, parasitism, or both.• We found that average shrub cover and nest height were the most significant factors upon the rate of parasitism (average shrub cover; F= 5.92, df =1, P = 0.02; nest height; F = 5.78, df = 1, P = 0.02).• The variables affecting nests which were predated after being parasitized were then ran through a logistic regression there was one significant correlation and that was between average visibility from the cardinal directions (effect = -5.79, Wald chi-square = 3.86, P = 0.04).

In conclusion, parasitism by brown-headed cowbirds increased the rate of predation upon indigo bunting nests and the nest site selection of the indigo buntings was important in determining whether the nest would be parasitized, predated, or both.

Brood parasitism affected levels of predation in our study. Another study (Payne and Payne 1998) found that nests with cowbird eggs are more likely to be predated. Successful nests were those with nest cups which were higher, in taller plants, and in denser shrub cover.

Literature CitedDEARBORN, DONALD C. 1999. Brown-headed cowbird nestling vocalizations and risk of nest predation. The Auk. 116(2):448-457.

PAYNE, R. B., AND L. L. PAYNE. 1998. Brood parasitism by cowbirds: risks and effects on reproductive success and survival in Indigo Buntings. Behav. Ecol. 9:64–73.

TEWKSBURY, JOSHUA J., MARTIN, THOMAS E., HEJL, SALLIE J., KUEHN, MICHAEL J., AND JENKINS, J. WAJID. 2002. Parental care of a cowbird host: caught between the costs of egg-removal and nest predation. Proc. R. Soc. Lond. B 269:423-429

Figure 2. Average shrub covers (%) in 5m radius from nests.

Our study showed that visibility of the nest is the most important factor affecting the rate of predation following an act of parasitism. This could be due to the fact that cowbird nestlings are larger, louder (Dearborn 1999), and in general increase the chances of a nest being predated. Often, parasitized yellow warbler (Dendroica petechia) females are more attentive to their nest and this increased commotion at the nest was found to increase the risk of nest predation (Tewskbury, et al. 2002). Though the driver behind the linkage between subsequent increases in parasitism and predation was not studied, a significant correlation was found.

Figure 1. Nest cup height (cm) among nests predated, parasitized, parasitized then predated, and successful nests.

Female indigo bunting and cowbird fledgling

Brown-headed cowbird adult

Indigo bunting male Indigo bunting nest

Identify three relationships among organisms that you observe in your environment.Try to list species names

Example: Red Oak instead of treeWrite them down and turn in as you leave.Try to think of examples that we haven’t used

yet. Determine what level of organization the

relationship would fall under.


Documents

Ecology