Comparative Primate Blog

Lemurs 

        

You can find Lemurs on the island of Madagascar. They tend to live in tropical rainforests but can also be found in dry and hot desert areas. Most lemurs live in high trees. All lemurs, except the ring tailed lemur, live in the high canopies of the rainforest trying to stay away from the ground. Ring tailed lemurs on the other hand spends most of its time on the ground. They do not possess gripping tails to hang from trees but they do have long noses and are very keen to smell. Unlike most monkey species, lemurs are lead by one dominant female. She leads the group and has first pick on food and her mates.  The smallest species of lemur can weight as much as 1 ounce and the biggest species can weight up to 15 pounds. Female lemurs tend to have more coloration than males do. For instance, in one species of lemur, the male is completely black but the female has a ring of white around her face and she is brown the rest of her body. This shows that a sexual dimorphism has evolved.

Spider Monkey

A spider monkey can be found in tropical forests in South America, as high as Mexico and as low as Brazil. They live in the upper layer of the rainforest in the canopy. They like an undisturbed rainforest for living. In the largest species of spider monkey (black spider monkey), males average to be about 24 pounds and females average about 21 pounds. They are usually between 14-26 inches long and have abnormally long tails, arms, and legs. The sexual dimorphism for spider monkeys is not noticable. Males and females have pretty much the same body size, shape, and weight. Facial and body structural features are the same in both male and females also. Since the spider monkey lives in high trees and rarely come to the ground, they do not need to be bigger or stronger than other species that might be a threat to them. Because of the environment they live in, males and females do not need to have any specific or defining features apart from each other. In this case, the environment caused little if any sexual dimorphism between male and female spider monkeys. 

             Baboon







The baboon can be found in East Africa in high trees, savannahs, or sides of cliffs. Anywhere around a water source with a comfortable living area.They spend most of their time on the ground walking on all fours. They do not have a gripping tails like most monkeys do so they are not the greatest climbers but they still do climb trees. Most baboons range from 40 in to 70 in and weight up to 90 pounds. Males are predominantly larger than females, almost twice as large. Males are also much more aggressive. This is because they must defend their territory against other predators and also to fight for dominance over females. Even though females are half the size of males, they have almost the same appearance except for the males ruff around their neck (long hair around neck like a mane). Males tend to leave their troop and fight for hierarchy and mates in other troops. Females are the ones who stay in their same troops from life to death. The sexual dimorphism of females not having the ruff around their necks probably has to do with evolution. They have to carry their babies around on their stomach and backs so the ruff would just be in the way. Males leaving troops probably has to do with mating. If all the females in a troop are taken, the males must go to different troops to find mates.  It is not necessarily environment factors but the species must be repopulated and if there is no inter troop breeding , then the species will eventually die down.

 Gibbon

 Gibbons are found in old growth tropical rain forests in southeast Asia ranging from Burma to Thailand. They swing from branch to branch up high in the trees. They do not build nests to sleep in, they rest on bare tree branches and the horny pads on their butts help for cushion. Both male and female Gibbons are about the same size, males tending to be slightly larger than females. They weight anywhere from 10-20 pounds. They possess long, extremely strong arms to swing from trees in the forest. They mark their territory by a screeching song that they sing to allow others to recognize the species and sex of that individual. Female Gibbons have smaller throat sacs which amplifies the frequency of its calls. This trait probably adapted because of the environment that gibbons live in. Since they live high in the trees and they are fast, identifying an individual could be difficult. If a threat were to come into their territory and they had no way of determining who it was, that could cause many problems. They females probably developed a different frequency call so that the males know who exactly they are and can recognize them without any problems.

 







Chimpanzee

The Chimpanzee can be found in many countries of Africa. They mostly reside north of the Congo River. They have been found in closed canopy forests which are extremely humid, and depending on the season, in dry forests and the savannah. When seen on the savannah, chimpanzees are usually migrating to another forest area. Because the chimpanzee has varied taste, they do not have a certain habitat that they must always be in. They are open for variety.   Male Chimps are larger than females. A male's height ranges from about 3-4 ft and a female's ranges from about 2-3.5 ft tall. Males usually weigh from 90-115 pounds and females weight from 57-110 pounds. Male chimpanzees are lager than females because they eat more than females. A sexual dimorphism trait that explains why males are larger than females is that females tend to leave and mate with other males while the males stay and defend and protect its territory. This trait was probably formed because chimps needed to breed to keep their species from being extinct and the males needed to protect their territory and resources to stay alive in order to reproduce. By males being bigger, it helps to defend what is theirs and to make sure that they won't be killed off.

Summary

Throughout this post, I have noticed that depending on the habitat of the species, the body size and sexual dimorphism differ. For example, with spider monkeys, gibbons and lemurs, the males and females tend to be about the same height and weight. They both live in the high trees of the forests and mostly stay off the ground. Because of this, they have no need to defend territory which means that size in this case doesn't matter. If there is no need for a dominant sex, then a species probably won't evolve into having one. Chimpanzees and baboons, on the other hand, live on the ground mostly. They have a dominant sex which defends their territory and fights for mates.  Males are much larger than females. Since they live on the ground, both species have to be bigger built to walk around all day and find food. Depending on the type of environment they live in, body size and sexual dimorphism changes. Monkeys that live mostly in the trees tend to be smaller with both sexes being about the same size and those species who live mostly on ground tend to be bigger built with the male being predominantly larger than females.

Homologous Trait : Wings

Dragonfly

The dragonfly is an insect with two pairs of transparent wings and an enlongated body with three distinct parts. They have six legs but most dragonflies can not walk well on them. They feed on mosquitos and other tiny insects. Dragonflies come from the order of Odonata. Their wings make them one of the fastest insects in the world.

Butterfly

The butterfly, like the dragonfly, also has two pairs of wings but instead of being transparent, they are covered in colorful scales. They have an elongated body with three parts, six legs, and they sip on nectar with their long tongue for food. Butterflies come from the order Lepidoptera. They are good fliers but can only fly if the temperature is above 86 degrees.

What is the Homologous trait?

In this example, the homologous trait would be the wings of both the dragonfly and the butterfly. Even though they serve the same purpose, they have completely different structures. A dragonfly's wing is transparent. There are very few veins in the wings as well. They are straight out and do not move well, meaning not flexible. But, because of their wings, they are able to fly sideways, backwards, make sharp turns, and even hover with ease. A butterfly's wings on the other hand are completely different. Their wings possess scales which give it their vibrant colors. Their wings have many veins and that is what keeps them warm enough to fly. Unlike the dragonfly, a butterly has a pair of forewings and hindwings. These do not stick straight out, they are attached to the thorax segment of their body and are flexible. So, the anatomy of both insect's wings are completely different yet provide the same service and purpose. This is a homologous trait.

Who is the common ancestor?

The common ancestor between the dragonfly and butterfly would be the insect. Even though a dragonfly is in the Odonata order and the butterfly is from the Lepidoptera order, they both are derived from arthropods which eventually evolved into insects. Not all insects have wings, but all insects have an exoskeleton, 3 part body, jointed legs, and antennae. So dragonflies and butterflies have evolved from the same common ancestor.

Analogous Trait:  Dorsal Fins

Shark

A shark is a big fish with no bones in it's body. It only has cartilage. It lives in the ocean and has up to 3,000 teeth at one time, replacing themselves if lost. A shark has 8 fins, are cold blooded, and are covered in scales that point towards the tail. They breathe through their gills by inhaling water. Sharks can't chew their food so they have to rip the flesh and swallow whole, which is why sharks do not have to eat as often as other animals. They can smell blood from miles and miles away which gives them a huge advantage since they mostly live in open water.

Dolphin

The dolphin is a marine mammal. This means that dolphins are warm blooded and breathe air through a blowhole located on the top of their head. They possess 2 pectoral fins, a dorsal fin, and a fluke (tail). These are used for fast swimming. Dolphins do not have any hair, unlike other mammals. They are known for being extremely intelligent animals and live in large pods together. They communicate by very loud frequency calls that are unique to each dolphin.

What is the analogous trait?

The analogous trait shared by the shark and dolphin would be the dorsal fin. Both the shark and the dolphin possess dorasal fins. They are both made of cartilage and not bones. The structure is the same and they are both used for the same thing which is to stablize the animal in water while it swims along with assisting turns. Although the shark is a member of the fish family and the dolphin is a mammal, they both have a common analogous trait of a dorsal fin even though they have not evolved from the same common ancestor.

Did the common ancestor possess this analogous trait?

It does not seem that the common ancestor of a dolphin and a shark shared this analgous trait. It is hard to determine if dolphins simply stayed in the water while other mammals eventually migrated out of the water or if dolphins and whales migrated to the water away from land. Since the shark has evolved from a fish which has always had dorsal fins and dolphins are from the mammal family which are not normally in teh water, it is safe to say that the common ancestor of sharks and dolphins did not possess this analogous trait.

Protein Synthesis :]

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Historical Influences on Darwin

Who Influenced Darwin's Theory of Natural Selection The Most???

From the 5 individuals listed that helped influence Darwin's theory of natural selection, I believe that Alfred Russel Wallace had the most influence. Wallace's discoveries of biological natural selection closed the open gaps in Darwin's research. He suggested that natural selection "selected" the dominant traits and "discarded" the weaker traits of organisms. This happened so that organisms can better adapt to their environment. Wallace came up with the theory that species came from other species and the change in facial structure or body parts is an effect of natural selection and evolution. Darwin and Wallace had very similar theories but Wallace's findings helped Darwin explain how it is possible
          http://evolution.berkeley.edu/evolibrary/article/history_14

The point that is most influenced by Alfred Wallace is the point that states "if the environment changes, the traits that are helpful or adaptive to that environment will be different." This point suggests that the "environment" selects what traits will be affective, natural selection. Wallace's discoveries were based solely on the process of natural selection. It is all about what will be the most successful traits to obtain in a population. So this point is definitely influenced heavily by Wallace and his ideas.

Because of Wallace's theory, Darwin was able to come to his conclusions about natural selection. It probably would have taken a long time for Darwin to understand truly how natural selection actually worked in nature. He had all of the correct assumptions, but without Wallace's idea of species evolving from other species, Darwin probably would not have figured out how variations in different species really occurred as fast as he did. Wallace's idea was the key point in explaning how natural selection is possible. So basically, without Wallace's ideas we would probably have had different understandings of natural selection and evolution for a longer period. Someone would have figured it out eventually, but it was a key point in Darwin's theory of natural selection.

Coming out with an alternative explanation for how we began to exist was a very controversial matter. The church obviously rejected any explanation other than being created by God. Because of the church's rejection to the theory of evolution, Darwin hesitated to publish any works on his discoveries and theories. He waited so long to publish anything because he knew that the church would convict him and see it as a threat. He only published his findings as soon as he did because he did not Wallace to recieve the credit for developing the theory of natural selection.