Question

1) what are the main probloms with reptalian systematics?

2) discuss the eveloution of jaws as it realtes to heterochrony, heterometey, heterotopy and hetetype?

3) compare the relationship to water in Lissamphibia and class reptilia?

Answer 1

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1)Systematic and taxonomic studies are essential for conservation – we can only preserve what we know. The first step of knowing organisms is to identify species, and to name and organize them according to their evolutionary history. The number of species of amphibians and reptiles has increased sharply over the last few decades, but we have much work ahead of us if we want to describe the outstanding biodiversity of the Neotropical herpetofauna. At the same time, traditional and emergent threats are accelerating the erosion of herpetofaunal biodiversity. Traditional threats include habitat loss, pesticides, and over-harvesting of wild populations. Emergent threats such as disease and climate change may impact species within natural protected areas where habitat loss and fragmentation are negligible. Emergent infectious diseases, such as chytridiomycosis, are associated with population declines and the collapse of amphibian communities throughout the Neotropics. Additionally, while climate change threatens many amphibian and reptilian species, it remains unclear how species will be able to cope with increasing temperatures, seasonal shifts and increasing frequency of extreme climatic events. The purpose of this special issue is to gather original studies focusing on herpetological systematics and conservation. We welcome contributions focusing on any Neotropical group of amphibians and/or reptiles, and which use original data or modeling of available data, aimed at improving the use of systematic and taxonomic knowledge for conservation. We also encourage papers proposing new methods to accelerate taxonomic studies, including those that present technological advances to quickly generate molecular data. This special issue will be open to all facets of conservation, ranging from applied conservation (i.e., to improve captive breeding programs, help design protected areas, or to design education projects) to policymaking and assessments of species threat status. We especially encourage reports of successful conservation initiatives that rely on the use of newly generated taxonomic information.

2)Jaws are thought to derive from the pharyngeal arches that support the gills in fish.Meckel's cartilage is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first gill arch (nearest the front) in early fish.

In evolutionary developmental biology, heterochrony is any genetically controlled difference in the timing or duration of a developmental process in an organism compared to its ancestors or other organisms. This leads to changes in the size, shape, characteristics and even presence of certain organs and features.

Heterotopy is an evolutionary change in the spatial arrangement of an animal's embryonic development, complementary to heterochrony.

The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of most animals.

3)

Although there are many differences between Reptiles and Amphibians, both are ectothermic, which means they are cold-blooded and need external sources of heat for thermoregulation (controlling their ambient body temperature). Below are a few of the key features differentiating the two:

Lissamphibia	Reptiles
These are cold-blooded animals.	These are warm-blooded animals.
They live on land as well as in water.	They live usually on land.
Their larval stage is spent in water and adulthood on land.	Their larval and adult stages are spent on land.
They are oviparous.	They are oviparous as well as viviparous.
Fertilization is external.	Fertilization is internal.
They can breathe through gills as well as lungs.	They breathe through lungs.
The heart is three-chambered.	The heart is three-chambered but the ventricle is further divided through a septum.
They secrete toxins from their skin to protect themselves from predators.	The skin is protected by hard scales, and they also secrete toxin through teeth and nails.
Skin is smooth and highly porous.	Skin is dry, hard and scaly.
The webbed feet help them to swim.	They have limbs to facilitate running and swimming.
Their eggs are covered with gel.	Their eggs are covered with a hard protective covering.
They have restrictions to narrow bands of the colour spectrum.	They can visualize and distinguish between different colours.