Chapter 16, Problem 15STP

Summary Introduction

To explain:

Importance of fossil records.

Introduction:

Evolution is referred to as a change in the characteristics of the organisms in a population over a period of time. These characteristics are hereditary and passed to the offspring. The key force which leads to evolution is Natural Selection. Stephen Jay Gould gave his theory on punctuated equilibrium in 1972 which challenged Darwin’s theory of evolution. According to Darwin, evolution is a gradual process whereas according to Gould’s theory, this led to branching speciation lead to splitting into two. This is known as Cladogenesis. Cladogenesis is the process in which a single species splits into two and give rise to two new species. Whereas according to Darwin, a single species continues to evolve under natural selection.

Explanation of Solution

Fossil records are the major key component in the study of the evolution of any species. Fossils are the sediments of bones and rigid structures that are found buried under the top layer of soil. They help us in understanding the morphological characters of the primitive species which got extinct. DNA obtained from fossils can also help us in the identification and study of the genes/genome of that primitive species. However, fossilization only possible for hard, rigid tissues/structures, soft tissues and other biomass can not be fossilized. Therefore, they were lost during the period of time, leaving the gaps between the fossils records for any species.

These gaps create difficulties in understanding the evolution of the species as some connecting links remain missing due to the non-availability of fossil records.

Conclusion

Fossil records can be absent for some of the intermediate species and thus creates the gap, this non-availability or gap of fossil records can be due to various factors such as lack of hard, rigid body structure, due to lack of preservative conditions, or due to more adverse environmental conditions which enhanced the degradation/decaying process of these structures. Ice, Amber, Peat bogs can preserve the fossils for a longer time as they reduce the decaying activity of soil. Hence, fossil records are crucial for accurate prediction of the evolutionary stages of any species.