PRIMITIVE MAMMALS IN AN EGG OR A POUCH? (2)

The topic of my presentation is primitive mammals. According to Solomon,
Villee and Davis (1985) mammals are thought to have evolved from a group
of reptiles called therapsids. These were dog-like carnivores with legs
adapted for running and differentiated teeth (considered a mammalian
trait). 'Non-reptilian' characteristics of the members included in this
group were pelvic and thoracic skeletal feutures which permitted the
legs to be positioned directly underneath the body
(http//tidepool.st.usm.edu/Crswr/therapsid.html). This development set
the stage for the evolution of the primitive mammals. In determining the
lower branches of the evolutionary tree of mammals, the following
features are studied:
1) The synapsid opening in the skull (a large hole behind the eye
socket for muscles that extend to the jaw, also found in early
relatives of mammals)
2) the three middle ear bones (used to classify all mammals)
3) the placenta
These traits correspond to eating, hearing, and reproduction functions,
and each represents an evolutionary branch.
(www.amnh.org/exhibitions/permanent/fossils/primitive.html)

Solomon, Villee and Davis (1985) states that by the end of the
Cretaceous period there were three main groups of mammals. These are
currently divided into three subclasses:
Prototheria. egg-laying mammals, also called monotremes. These are
represented by the extant duck-billed platypus
Metatheria.pouched mammals, also known as marsupials. These are
represented by opossums, kangaroos etc.
Eutheria. placental mammals.
The fossil record describes the Cretaceous (146-65.5 MYA) as a period
when the first fossils of many insect groups, modern mammal and bird
groups, and the first flowering plants were found
(www.ucmp.berkeley.edu/mesozoic/cretaceous/cretaceous.html). This
presentation will deal with origins and evolutionary developments of
primitive mammals. It will also explore the conditions/developments that
enabled the survival of the Prototheria and Metatheria (primitive
mammals).

Dane McDonald
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Dane McDonald
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

PLACENTAL CARNIVORES, PAST AND PRESENT

In the Crataceous period of the Mesozoic era mammals began to expand
and 120 million years ago Marsupials and Placentals diverged in the
mammal lineage. In the Paleocene epoch of the Cenozoic era 65 million
years ago mammals began to rapidly expand. Two major groups diverged in
this epoch the now extinct Creodonts which dominated 55 million years
ago and the true carnivores (order Carnivora) which still flourishes
today.(www.bobpickett.org/TIMELINE.htm)

I'll be looking at the common ancestor, some suspicion does exist on
whether the two orders does in fact share a common
ancestor.(www.enwikipedia.com) Major groups, characteristics and
habitat of the two orders. Similarities and differences in dentition,
body plan, brain size, diet , locomotion amongst others,and try to
ascertain whether these factors played a role in the extinction of one
order and the radiation of the other. I'll also be looking at newly
discovered carnivore species.

Ilse Kotzee
Student # 2456349
2456349@uwc.ac.za

CRUSTACEANS - JOINTED APPENDAGES FOR LOCOMOTION & FEEDING

In this report I will cover most of the features that makes up the physical characteristics of crustaceans, which includes a brief description of what crustaceans are and why they are the most diverse group of marine arthropods and ecological importance of crustaceans.

Crustaceans are a large group of arthropods that are treated as a subphylum and are found in marine, freshwater and terrestrial environments although they are mostly found in aquatic ecosystems. They have three distinct body divisions that include the head, the thorax or when there is no clear distinction between the head and thorax then it's called the cephalothorax, they are metameric and the appendages are segmented, there are usually five pairs of appendages strengthened for walking, protection and feeding.

The most important groups found abundantly of the crustaceans are the copepods, barnacles, malacostraca (Craps, shrimps, lobster and krill), branchiopoda. Groups that posses a well developed abdomen, usually have six specially adapted appendages for locomotion of which 5 are called swimmeret (pleopod) and one pair called the uropods, which can be combined with the terminal telson from the tail fan to serve as rudders in locomotion. The scientific classification of the crustaceans reads as follows:

Kingdom:     Animalia
Phylum:       Arthropoda
Subphylum: Crustacea
Class:          Branchiopoda 
                    Remipedia 
                    Cephalocarida
                    Maxillapoda
                    Ostracoda
                    Malacostraca
Source: www.Wikipedia.com

The exoskeleton is divided into a number of plates and cylinders; the jointed appendages are described as the point where the exoskeleton remains flexible and thin at the junction of the plates and cylinders, which allows the crustaceans to move more efficiently.

Many of the crustacean's appendages are biramous, which means that the appendages have an outer exopod and an inner endopod. They have a hardened exoskeleton that contains calcium carbonate. The head bears a pair of compound eyes and three pairs of mouth parts, which are a pair of mandibles and two pairs of maxilla used for handling food.

They have biphasic life cycle changing around the larval and juvenile phases and is common in most marine invertebrates, which suggest that the earliest levels of metazoan evolution had this type of life cycle (Hans et al 2002).

Crustaceans have a constant feeding activity and will undergo certain times of fasting during development, which occurs through molting (Sanchez-Pazza et al 2004). Molting involves different stages with different feeding behaviors and requires sufficient energy from the food available to crustaceans (Sanchez-Pazza et al 2004)

References: http://faculty.evansville.edu/de3/b10802/PPoint/Arthropoda/10-Arthropod.ppt .
http://en.wikipedia.org/wiki/Crustaceans

A Sanchez-Paza,b, F Garcý a-Carren oc, A Muhlia-Almaza, A B. Peregrino-Uriarteb, J Herna ndez-Lo pezb, G Yepiz-Plascenciab, (2004) Usage of energy reserves in crustaceans during starvation: Status and future directions, Centro de Investigaciones Biolo´gicas Del Noroeste (CIBNOR), Unidad Hermosillo, Centenario Norte #53 Col. Prados Del Centenario, Hermosillo, Sonora C.P. Mexico

Hans U. Dahmsa, John A. Fornshellb, Ben J. Fornshellc(2002) Key for the identication of crustacean nauplii,Department of Systematic Biology, National Museum of Natural History, Smithsonian Institution, Washington, USA

 

Ashton Mouton
Student Number: 2432509
University of the Western Cape
Private Bag X17
Bellville 7535

 

E-mail: 2432509@uwc.ac.za

ANGIOSPERMS-FLOWERING PLANTS HAVE ARRIVED

Angiosperms are floweing plants that bear reproductive organs:androecium (male) and/or gynoecium (female) in the flower structure;they also cover their seeds in a true fruit (http://en.wikipedia.org/wiki/Angiosperms#History)  .More primitive angiosperms would be monoecios ie. their male and female organs are situated on separate flowers , whereas modern angiosperms are dioecious ie. their male and female organs are situated on one perfect flower, this is also known as being hermaphrodite (http://en.wikipedia.org/wiki/Angiosperms#History) .Angiosperms constitute the dominant land vegetation of the Earth's surface (http://en.wikipedia.org/wiki/Angiosperms#History) .

 

During the Cretaceous era (145-65 million years ago) saw the rise of flowering plants and their associated insect pollinators by the process of co-evolution (http://www.geocites.com/we_evolve/Plants/angiosperm.html) Although the first fossil evidence of angiosperms appeared in the fossil record approximately 140 million years ago (Jurassic era). This co-evolution between plants and insects was most probably the most influential driving force behind the origin and diversification of angiosperms, although it has been disputed that seed production, dispersal and seedling establishment was the most important angiosperm origin (http://www.geocites.com/we_evolve/Plants/angiosperm.html) .By the late Cretaceous angiosperms became the most dominant group of land plants (http://en.wikipedia.org/wiki/Angiosperms#History) .

 

The success of angiosperms can be attributed to the mutualistic relationship with pollinators, as angiosperms have counter adapted to prevent pollinators from consuming pollen and seeds (http://www.as.wvu.edu ) , counter adaptations include the production of nectar and seeds inclosed in a fruit as pollinators consume the fruit that surrounds the seeds ,therefore sparing pollen and seeds and playing a major role in pollen and seed dispersal (http://www.as.wvu.edu ) .

 

 

 

 

Simone Neethling
BCB Department
University of the Western Cape
241343632@uwc.ac.za

Annelid diversity

The annelids or the "segmented worms" are distinguished from other worms on the basis of metamerism and the presence of chaetae. ( http://en.winipedia.org/wiki/Annelids ). Annelida is a successful phylum with members of this group globally distributed occupying a range of terrestrial and aquatic habitats ( http://en.wikipedia.org/wiki/Annelids ).

The first fossil record was that of the polychaeta Canadia found during the Cambrian and late precambrian ( http://en.winipedia.org/wiki/Annelids ). According to http://en.wikipedia.org/wiki.annelids/Annelida.htm , there were several likely appearances of polychaetes during the Ordovonian (that of Serpulidae, Spionidae ). The Ordovonian also marked the Eunicida radiation.Thus by the end of the carboniferous, most polychaete lineages had appeared.

The annelids are thought to have evolved from and be closely related to the arthropods ( http://en.wikipedia.org/wiki/Annelids ) because of shared segmentation. However recent molecular data suggest that the shared segmented character of these two groups may be due to convergence rather than a sign of homology. Thus, this shared segmentation is due to shared functional requirements of these two groups rather than indicating common decent.

Recent molecular evidence suggest that annelids are closely related to the mollusks because they both have trochophore larvae as a developmental stage in their life cycle ( http://en.wikipedia.org/wiki/Annelids ).

The large success of the annelids can be contributed to the fact that they are capable of both sexual and asexual reproduction. Asexual reproduction and regeneration during injury gave many species a competitive advantage over other species. Sexual reproducing species can be monocious or diocious which allowed these organisms the rapidly adapt to changing environmental conditions ( http://en.wikipedia.org/org/wiki.Annelids/reproduction ).

Presently, three major subclasses of annelids are distinguished, namely the oligochaetes (Oligochaeta), polychaethes (Polychaeta) and leeches (Hirudinea) ( http://en.wikipedia.org/wiki ). The polychaetes are mainly marine. They are adapted with parapodia containing bristles which are used in locomaotion and respiration. The polychaetes are free living or tube dwelling, while others can be commentially associated with other organisms ( http://en.wikipedia.org.wiki ). The oligochaetes (including terrestrial earthworms) have fewer bristles than polychaetes and also lack parapodia, which would not be of much use for life on land.The Hirudinea are thought to have evolved from detritus eating earthworms ( http://en.wikipedia.org.wiki ). These members of annelida can be parasitic or haemophagic parasites, feeding on the blood of vertebrates.

Despite the relative success of the phylum annelida, members such as the Lake pedder earthworm ( Hypolimnus pedderensis ) which were found mainly in Australia and Tasmania have gone extinct (http://www.redlist.org/search/details.php?species=6828). Members such as the Giant Palouse earthworm ( Driloleirus americanus) are currently vulnerable to extinction while member such as Hirudo medicinalis that is native to Europe are at low risk. Extictions are mainly contributed to habitat loss or degredation due to increased agricultural activity and infrastructure development (http://www.redlist.org/search/details.php?species=6828).

 

 

M.van der bank
2401402@uwc.ac.za

 

 

Insectivores- primitive placentals

Insectivores- primitive placentals

These are animals under the phylum Chordate and within the class
mammalian. They are called insectivores due to the fact that they are
almost entirely insect eating animals. The Order insectivore includes
groups like shrews, hedgehogs, gymnures, tenrecs, otter shrews, moles,
desmans, solenodons and golden moles.
They are characterized by the by the traits that they are:
1. Among the smallest mammals.
2. Their senses of vision and touch are poor and thus compensated
by an outstanding sense of smell and hearing.

Insectivores are quite diverse with a genera of 65 and 439 species.
This abundance could be attributed to their diet of insects. They are
considered to be the most primitive of placentals, because their
morphological characters are considered to be primitive and common to
the earliest ancestors. These morphological characters include:
1. Pent dactyl, with generalized plantigrade locomotion.
2. Small braincase and a brain with smooth cerebral hemispheres.
3. Primitive dentition.
4. They tend to be small to medium in size.

The earliest known fossil within this Order is from the cretaceous
period, it was found somewhere in North America at about 100 million
years ago. Insectivores are of little or no economic importance. The
main thing that threatens their existence is the loss of habitat. This
is of importance because they are tropical species. They are found
throughout the world except for Australia, South America and Polar
Regions. In my assignment I will then look at the major issues coming
through, these include:
1. When did insectivores evolve?
2. Why they are considered primitive.
3. What is so special about the habitats they occupy?
4. What is their conservation status?

In trying to tackle this topic I will first look at their origin and
what has made them last for as long as they have. It is assumed that the
insectivores descended from one common ancestor, this is thought so
because they are the least evolved when one looks at their prevailing
morphology. They evolved during the cretaceous period at approximately
125 million years, insectivore mammals like purgatories evolved as tree
dwelling.
Now the second part of this would be to look at their distribution. As
mentioned above they have places which they inhibit, this could be due
to the fact that particular environments are favorable to them. The
resources and climate change within these areas are within coping range.
When one compares South America with other tropical areas that the
insectivores live in there is a dramatic difference in the climate one
region is very cold while the others are somewhat of average climate.

References:
1. www.ingentaconnect.com/content/
urban/161/2003/00000068/00000004/art00005
2. www.life.umd.edu/classroom/ bsci338m/Lectures/Insectivores.html
3. www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve
4. msc.bhsu.edu/biology/bsmith/mammlec9.html

Dlamini L.N
2449510@uwc.ac.za

PRIMATES - LIFE IN THE TREES

Primates are categorized into three major groups, the Presimians (e.g. Lemurs), the New World Monkeys (e.g. Squirrel Monkeys) and the Old World Monkeys (e.g. Gorillas). Definitive features of primates are a pentadactyl limb with an opposable thumb. Humans share a genetic sequence of 99% with chimpanzees, classifying them as modern apes.

My assignment will cover the classification with distinct similarities and unique features of each of the three groups. Along with this I will place them in the evolutionary line of all organisms and what makes primates different from all other organisms.

I will also look at the biogeography of each of the three groups and look at how location and climate affect the lifestyles and adaptations of each group. Also I will look at the biological relationship of humans with other apes and how different and similar they are.

Over 100 species, approaching half of all primates, are threatened or endangered. The tropical forests where most primates live are disappearing at an alarming rate. Gorillas are one of the predominant species under threat. This mostly occurs in countries in turmoil and so conservation of species is difficult. Jane Goodall and others who have done field studies of primates in their natural habitat have shown that dedicated individuals are one of the keys to successful conservation.

 

Anzio Abels
Biodiversity & Conservation Biology Department
University of the Western Cape
2429667@uwc.ac.za

 

 

Insectivores- primitive placentals

Insectivores- primitive placentals

These are animals under the phylum Chordate and within the class
mammalian. They are called insectivores due to the fact that they are
almost entirely insect eating animals. The Order insectivore includes
groups like shrews, hedgehogs, gymnures, tenrecs, otter shrews, moles,
desmans, solenodons and golden moles.
They are characterized by the by the traits that they are:
1. Among the smallest mammals.
2. Their senses of vision and touch are poor and thus compensated
by an outstanding sense of smell and hearing.

Insectivores are quite diverse with a genera of 65 and 439 species.
This abundance could be attributed to their diet of insects. They are
considered to be the most primitive of placentals, because their
morphological characters are considered to be primitive and common to
the earliest ancestors. These morphological characters include:
1. Pent dactyl, with generalized plantigrade locomotion.
2. Small braincase and a brain with smooth cerebral hemispheres.
3. Primitive dentition.
4. They tend to be small to medium in size.

The earliest known fossil within this Order is from the cretaceous
period, it was found somewhere in North America at about 100 million
years ago. Insectivores are of little or no economic importance. The
main thing that threatens their existence is the loss of habitat. This
is of importance because they are tropical species. They are found
throughout the world except for Australia, South America and Polar
Regions. In my assignment I will then look at the major issues coming
through, these include:
1. When did insectivores evolve?
2. Why they are considered primitive.
3. What is so special about the habitats they occupy?
4. What is their conservation status?

References:
1. www.ingentaconnect.com/content/
2. www.life.umd.edu/classroom/ l
3. www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve
4. msc.bhsu.edu/biology/bsmith/mammlec9.html

Dlamini L.N
2449510@uwc.ac.za

INSTRUCTIONS FOR THE BIODIVERSITY PRESENTATION

The biodiversity will count 50% of your year mark.

You will be given 3 Practical periods to obtain information for your presentation

The presentation should be at least 25 slides long and prepared using Power Point and a supplied template.

Notes are to be appended to the presentation (approx 5000 five-thousand) and should be referenced.

If you lift images from the Internet provide the URL acknowledging their source.

Provide a clear structure for your outline under informative headings e.g.

When did the group first appear?

Describe the first forms physically and in which geological periods did this occur?

What were the environmental conditions that operated at the time of this evolutionary breakthrough.

How successful were they, what ecological niches did they occupy?

What were the more successful forms and identify key features to their successors

Did their genes survive until today and for how long were they successful?

Track their evolution to either today or to the time of their extinction

If extinct, what contributed to their extinction?

If extant, how successful are they today, what limits them and what is their conservation status, range and habitat occupation?

Identify key feature contributing to their success of failure of the group.

Descripe the major groups that live today and indicate their current vulnerability within each of these major group.

What is/are the ecological/economic value of the group or individual species?

Are there any species of especially interest e.g. living fossils?

Under climate change are they likely to be an increaser/decreasers species?

PRIMITIVE MAMMALS IN AN EGG OR A POUCH?

The topic of my presentation is primitive mammals. According to Solomon,
Villee and Davis (1985) mammals are thought to have evolved from a group
of reptiles called therapsids. These were dog-like carnivores with legs
adapted for running and differentiated teeth (considered a mammalian
trait). Furthermore the fossil record shows that early mammals were
quite small or similar in size to a mouse or shrew.

Solomon, Villee and Davis (1985) states that by the end of the
Cretaceous period there were three main groups of mammals. These are
currently divided into three subclasses:
Prototheria. egg-laying mammals, also called monotremes.
Metatheria.pouched mammals, also known as marsupials.
Eutheria. placental mammals.
I will limit my presentation to the Prototherians and Metatherians
because they are considered primitive in comparison with the placental
mammals. The latter form of reproduction was last to evolve.

My main aim is to discuss as well as to compare the reproductive
strategies of the above mentioned groups.

Dane McDonald
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535