The main physical barriers—the body’s first line of defense—are the epithelial layers of the skin and of the mucosal and glandular tissue surfaces connected to the body’s openings

TLS Online TPP Program

#Id: 9424

#XL - T Zoology

Parental investment - Parental investment refers to the contributions each sex makes in producing and rearing offspring.

TLS Online TPP Program

#Id: 9426

#XL - T Zoology

TLS Online TPP Program

#Id: 9427

#XL - T Zoology

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#Id: 9428

#XL - T Zoology

A- Parental investment is high in females than male

Reason - Eggs are much larger than sperm.

Females are responsible for gestation and lactation.

B - Parental investment is high in males than female - very rare

Male Mormon crickets transfer a protein-containing spermatophore to females during mating. Almost 30% of a male’s body weight is made up by the spermatophore.

C- Parental investment of males is equal to female

Degree of mate choice should be equal between the sexes.

No sexual dimorphism

Present in bird

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#Id: 9429

#XL - T Zoology

TLS Online TPP Program

#Id: 9430

#XL - T Zoology

Bateman’s principle

In most cases, it is the male’s secondary sexual traits that are exaggerated.

This shows that sexual selection is more common and intense on males than females