Coleop-Terra Adaptation and Speciation of Beetles

Enviromental-Factors Adapted-Variants Speciation Mimicry

In large species like Goliathus an initial period of activity to raise the thorax to a temperature at which flight is possible is all that is required.
The population of black phenotype without hypodermal pigmentation is noticeable predominantly in closed forest. Perhaps because of its dark pigmentation, the nominate form cannot tolerate high incident sunlight, or higher operative temperatures, leading one to predict that it would live in a shady habitat or have crepuscular or nocturnal activity patterns.

Conversely, this species' black pigmentation may be selectively advantageous for heating up faster in cooler environments. In regions with open forest the luminosity probably plays another role for Goliathus. White shining hypodermal pigmentation of the elytras could avoid overheating. The pale grey on elytra and thorax of the Goliathus beetle is a hypodermal colour that occurs outside of the animal. The hypodermal colours are the only ones on which the animal has any influence, either involuntarily by the action of the nutritive fluid, or voluntarily. The epidermal cells are placed entirely outside of any influences of the animal, when once established.

Adapted variants

The aberrations of Goliathus goliatus may be a result of different change of biological parameters. A lot of white variants can be found in Cameroon or northern-Congo. Goliathus goliatus orientalis is located in Southern Congo, Zambia and southern Tanzania. Goliathus goliatus orientalis preissi usambarensis is more localised in forest of central and North Eastern Tanzania.

White variants of Goliathus goliatus from northern equatorial africa

Black variants of Goliathus goliatus from central equatorial africa

White variants of Goliathus goliatus from south/eastern equatorial africa

Speciation

There is an assumption that specimens of the common ancestor of Goliathus regius (1), Goliathus cacicus (2) and Goliathus goliatus (3) were isolated from each other by the Cameroon mountains. They were split into isolated gene pool pockets. Because of genetic isolation from each gene pool, new species are derived.

Mimicry

Anthia (Fig. a.) is a genus of groundbeetles which is protected by a fluid it sprays at attackers.
Juvenile Lizards (Fig. c.) of several sand lizards are black and white like species of Anthia. Adult lizards are coloured with the red-tan colours of the Kalahari semi-desert. While the adult Lizards move typically lizard-like, the juveniles move with stiff, jerky movements with their backs strongly arched and with the paler-coloured tails pressed to the ground. When juveniles change to adult colouration, the arch-walking behaviour is 'switched off'.
To evaluate how effective the mimicry was against predation, researchers examined the tails of various sympatric (occupying the same region) lizard species for evidence of damage and comparisons were made between mimicking and non-mimicking, paler-coloured lizard species. The results showed that there were more damaged tails among the latter group than the mimicking group. It was also found that arch-backing juvenile lizards were avoided in 100% of interactions with snakes but were attacked if they moved normally. The domino cockroach Therea petiveriana (Fig. b.) from India also avoids predation through mimicry, it is patterned like Anthia sexguttata.