The Ecology Book

32

L

ong before scientists

cracked the genetic code,

in 1866 an Austrian monk

named Gregor Mendel was the first

to show how traits are transferred

through the generations. By means

of much painstaking research,

Mendel accurately predicted the

basic laws of inheritance.

When Mendel began his

experiments, scientists believed

that the various traits seen in

plants and animals were handed

down through a “blending” process.

However, Mendel noticed that this

was not the case when he was

working in his monastery garden.

When he crossed a plant that

always produced green peas with

one that always produced yellow

peas, the result was not yellowish-

green peas—instead, all the peas

were yellow.

Mendel’s labors

During the course of his research

(1856–63), Mendel grew nearly

30,000 pea plants over several

generations and carefully recorded

the results. He focused on traits

IN CONTEXT

KEY ECOLOGIST

Gregor Mendel (1822–84)

BEFORE

1802 French biologist Jean-

Baptiste Lamarck suggests

that traits acquired during the

lifetime of an organism are

transmitted to its offspring.

1859 Charles Darwin proposes

his theory of evolution and

natural selection in his book

On the Origin of Species by

Means of Natural Selection.

AFTER

1869 Swiss chemist Friedrich

Miescher identifies DNA,

which he terms “nuclein.”

1953 Molecular biologists—

including Briton Francis

Crick and American James

Watson—discover the

structure of DNA.

2000s Researchers in the

field of epigenetics describe

inheritance by mechanisms

other than through the DNA

sequence of genes.

HUMAN BEINGS

ARE ULTIMATELY

NOTHING BUT

CARRIERS FOR GENES

THE RULES OF HEREDITY

F1 GENERATION

all yellow

PARENT GENERATION

1 green 1 yellow

Mendel’s pea experiment

Mendel’s

experiment

with growing peas

proved that the gene

carrying the yellow

coloration was

dominant while the

gene for green was

recessive.

F2 GENERATION

1 green 3 yellows

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