Custom Biology Essay Examples

An Investigation into the Accuracy of Classical Behavioural Ecology Concepts, such as Ideal Free Distribution, using the Model Organism Folsomia candida

Since the days of early ethologists Karl von Frisch and Konrad Lorenz, behavioural ecologists have attempted to devise simple sets of rules to explain and predict the, often complex, behaviour of animals. One of the most prevalent of these sets of rules is the theory of Ideal Free Distribution (Fretwell & Lucas 1970); the theory predicts that individual organisms will arrange themselves proportional to the amount of resources in each separate "patch". In order to make this prediction, the theory relies upon the assumptions that: resources are distributed equally among patches; that all competitors are equal, negligible travelling costs, there is no depletion of resources and that predators of the subject are omniscient1. These are unrealistic assumptions to make of a system in the wild, but how does the theory fare at predicting behaviour in a controlled system? This is the question the first section of this manuscript intends to answer. The second section will address the functional responses to prey density.[…]

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Animal Models in Behavioural Neuroscience The Light-Dark Box Experiment

Introduction

The light - dark box (LD box) is a much replicated procedure; it is a simple yet effective way of quantitatively measuring the response of a mouse to light. It has been used in countless experiments to investigate everything from neuropharmacokinetics to behavioural psychology. The aim of this experiment is to explore the difference between different strains of Mus musculus.

Method

The light-dark box was set up as above; extra illumination was provided in the light section via a 60W anglepoise lamp. Three replicate mice of two strains were introduced into the centre of the light section of the box facing away from the dark section. The strains used were female C57BL/6 from Cage A and female C57BL/6/129 from Cage C. The number of milliseconds each mouse spent in each section was recorded along with the number of transitions between the light and dark sections. Results[…]

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Ant Diversity Along an Amazon - Andes Altitudinal Gradient

A key question that has interested ecologists for decades is how species and communities respond to their environment. Understanding this can help ecologists to determine how fluctuations in climate, the presence of invasive organisms or other disturbances may influence natural systems. Recently there has been a resurgence in montane research in an attempt to answer some of these questions (e.g. Lomolino, 2001; Rickart 2001). Mountains have become one of the last refugia for a large, albeit undetermined number of species, and it is essential and timely that ecologists once again take up the challenge of describing and understanding patterns of biological diversity of montane ecosystems (Lomolino, 2001). Altitudinal gradients provide an ideal set-up to explore how factors such as energy and water availability, and habitat type and heterogeneity affect diversity (Rahbek 1995, Sanders 2002, Botes et al. 2006, Sanders et al. 2007). This project thus aims to investigate changes in the composition of ant assemblages along an altitude gradient in Peru from the lowland Amazon rainforest, through to the highlands, and link ant diversity to various biotic and abiotic habitat measures (including vegetation cover, litter load, productivity, temperature, rainfall). The altitudinal gradient in the study spans 3431m, ranging from 194m asl in the lowland […]

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Animal Navigation and Maps

For hundreds of years people have been puzzled about the mechanism behind the extraordinary homing abilities of the domesticated pigeon (Columba livia domestica). Many studies have been conducted into finding a possible explanation, such as the famous clock shift experiment of Neuss and Wallraff (2004) which used pigeons subjected to artificial day / night conditions to alter their circadian rhythm in order to prove that "home orientation" is largely light dependant and that the "sun compass" is an important tool in avian navigation.

Our experiment involves the use of circular statistics in order to determine whether a significant number of individuals "vanish" in a homeward bearing out of a sample consisting of ten birds released 25km south of their lofts.

Hypothesis: a statistically significant number of individuals will vanish with a heading comparable to the homeward component

Results: In order to collect the data, 10 pigeons were released at an average rate of one 520s-1. The individuals were observed with binoculars until out of sight, at which point a compass bearing was recorded. The results are displayed in Figure 1.From the data, the Mean Vector (f) was calculated as 12º (see Appendix). The Rayleigh Test to establish the degree of randomness of the sample returned a value of 0.205 suggesting that the sample was significantly non-random. By using the homeward value v (0.380172), u was calculated and found to be greater than its table derived counterpart thereby proving that the null hypothesis can be rejected. […]

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Techniques in Molecular Biology 1. Investigating Microbial Ecology Using Molecular Techniques. Does Ocean Acidification Affect Bacterial Diversity?

Abstract

The increasing number of oceanic bacterial species discovered in recent years has inspired many studies into their taxonomy. This study is concerned with how oceanic bacterial species diversity will change in the future. Based upon current research; the assumption is made that increased atmospheric CO2 partial pressures will cause a significant drop in oceanic pH. The experiment was conducted in Bergen (Norway) where 6 mesocosms each containing 12 metric tonnes of native seawater were subject to different environmental conditions. The data was obtained by sequencing and comparing 16S rRNA genes from bacteria extracted from the ambient and high-CO2 environments. Species were identified primarily by searching the BLAST (Basic Logical Alignment Search Tool) databases. The results and statistical analysis show a significantly larger number of bacterial species are able to survive in the high CO2 environment (future conditions) compared to the ambient environment (current). For reasons why this occurs we look more closely at each species and its role in the ocean ecosystem. From the findings it is clear that further study is needed in order to comprehend the complex interactions between different groups of microorganisms and also their interactions with the environment. […]

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