Mohd-Azlan et al. (2014). Resource Partitioning by Mangrove Bird Communities in North Australia. Biotropica 46(3): 331340.

Reading Materials

Mohd-Azlan et al. (2014). Resource Partitioning by Mangrove Bird Communities in North Australia. Biotropica 46(3): 331340.

Concept 54.1 - Ecological Niches & Natural Selection and Character Displacement. Campbell Biology, 11th Ed or 10th Ed. (Online access available at UniSC Library)

For bird morphology and images: Birds of Australia: A Photographic Guide, Campbell et al. 2014, Princeton University Press (Online access available at UniSC Library)

Refer to Tutorials 1-4 materials and weekly Learning Materials if needed.

Background

This week we will explore the concept of the niche, and how it provides a framework for understanding how so many species can coexist in one place and the role that it plays in the evolution of new species. This tutorial exercise, including both the vocabulary part and the critical thinking questions will be submitted via Turnitin on Canvas by 5pm Friday, 30 September 2022.

Firstly, lets revisit what you learnt from the second tutorial reading and exercises. In that tutorial, you explored the mechanism through which new species arise. Of paramount importance is the development of reproductive isolation among a subset of a previously freely interbreeding population(s) of a species. Naturally, the individuals of this new subset of organisms must not only be reproductively isolated from the parent population, they must also be reproductively compatible with one another.

It is theorised that reproductive isolation can come about as a result of behavioural or physical changes in the new species, or as a result of genetic changes that occur during reproduction. We will focus on the non-genetic mechanisms here.

Changes in behaviour and morphology arise as a consequence of the ancestors of the new species changing (evolving) such that they better suit a new environment. This new environment can be an entirely different habitat (geographic or allopatric speciation), or simply a different microhabitat within the original habitat (sympatric speciation). Whatever the context, the underlying assumption is that as the organism evolves to suit a new niche, it becomes behaviourally and/or morphologically unable to reproduce with its parent species.

Aside from its implicit role in the generation of new species, the niche is also of paramount importance when it comes to understanding how communities of organisms are able to co-exist. This co-existence is facilitated by partitioning the available resources within a habitat. This weeks readings explore the niche in broad terms (Campbell Biology reading) and in finer detail via a niche study of mangrove bird communities in north Australia (Mohd-Azlan et al. 2014).

Approach to Assessment Task 2

(i) Complete the vocabulary exercises and the reading comprehension and critical thinking exercises prior to coming to your tutorial class in Week 11;(ii) Use discussions and feedback during the class to improve on your answers;

(iii) Take your work home and improve it;(iv) Submit your final Tutorial 5 work via Turnitin on Canvas by 5pm Friday, 30 September 2022.163195626110Turnitin is a plagiarism detection and prevention tool that checks submitted work for originality.

00Turnitin is a plagiarism detection and prevention tool that checks submitted work for originality.

Grading: This assessment task is worth 35% of the total course mark. The breakdown of these marks is:

10% - vocabulary builder, Tutorial 5.

25% - reading comprehension and critical thinking exercises, Tutorial 5.

Please complete the provided readings and answer the following questions by typing into the spaces after each question. Be sure to include your name, student ID, and your tutor name in the header at the top of the document.

Critical Vocabulary encountered in this weeks readings: Please define these terms in the CONTEXT of this article. Each definition is worth 1 mark.

VOCABULARY DEFINITION

1 Community (in this case - birds) assemblage 2 Relative abundance 3 Resource (niche) partitioning 4 Habitat utilisation 5 Sympatric species 6 Flowering phenology 7 Nectarivore 8 Insectivore 9 Character displacement 10 Habitat complexity Reading comprehension and critical thinking

Background

The questions below are designed as discussion points to be worked on prior to, and during your tutorial class. You will need to be able to refer to the readings nominated for this weeks tutorial exercises, so make sure you bring them with you. It is important that you talk about these questions and that any unclear points are resolved in the tutorial.

Exercises

As a guide to help you answer the following questions with the appropriate level of detail, you are provided with the number of marks that each question is worth, and a word guide for each answer. The word guide is intended as a general guide only. This part has 25 marks in total.

Tutorial exercises

What is a niche? Can two or more species with the same niche coexist? (2.5 marks) (~60 words).

What is the relationship among habitat complexity, number of available niches, and biological community diversity? Use an example to explain the relationship. (2.5 marks) (~60 words).

The niche of an organism can be broken down into different components or dimensions, including dietary niche, activity niche etc. Mohd-Azlan et al. (2014) used this approach in their exploration of bird niches in the mangroves in north Australia. Use dot points to list and briefly describe each of the niche dimensions that the authors investigated in their study (2.5 marks) (~60 words).

How does niche partitioning facilitate the coexistence of 20 terrestrial bird species investigated in Mohd-Azlan et al. (2014)? Answer this question using examples from this journal article (5 marks) (~150 words).

Pick any two of the bird species dealt with in Mohd-Azlan et al (2014). Now imagine that one of these species is descended from the other as a result of speciation through adaptation to a new niche.

Using morphological, habitat and other niche data provided in the reading and from your own literature search, speculate on at least two changes in behaviour or morphology that might have accompanied the birds adaptation to its new spatial niche (see Table 1 and Table 2 in Mohd-Azlan et al. 2014 for niche dimension information). Speculate on how the shift to the new spatial niche may have resulted in intrinsic reproductive isolation of that species from its parent species. In answering this question be sure to be clear which two bird species you are talking about. (12.5 marks) (~300 words)

Note: Mohd-Azlan et al. (2014) did not provide morphology information for the bird species they studied. You will need to search literature to get information about the morphology of the bird species you choose for this exercise. Birds of Australia: A Photographic Guide by Campbell et al. (2014) is a good source for bird morphology information and can be accessed online via USC Library. You should use bird images to help you describe bird morphology and make sure you cite the sources of the images you use.

HAVE YOU ENTERED YOUR PERSONAL AND TUTOR DETAILS INTO THE HEADER OF THIS DOCUMENT?

IF YOU DONT KNOW YOUR TUTORS NAME TUTE 5 IS AN IDEAL TIME TO FIND OUT!