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Colonization pathway of Heliconius charithonia L. and range overlap of tropical butterflies in Texas.

Cardoso, Marcio*,1, 1 Universidade Federal do Rio Grande do Norte, Natal, Brazil

ABSTRACT- Each year, tropical butterflies such as the zebra, Heliconius charithonia colonize Texas. Although it is a common phenomenon, there have been few attempts to analyze the pattern of colonization. Data from such studies can be of great importance in the analysis of species invasions and colonization. This study addresses the seasonal advances of the tropical butterfly H. charithonia into temperate Texas, using information from natural history notes compiled by an amateur entomologist, spanning more than 100 years. The data consisted of the date and locality when individuals were collected and/or observed. For all data points I noted date of first sighting, distance from presumed source and residency time (in months) in site collection. There is a clear colonization wave expanding north, beginning in March and ending in December, when cold weather presumably curtails advance by killing colonizers. The colonization does not seem to be random: collection sites are located in a central-eastern area of the state. Butterfly absence from north and west areas is probably due to inadequate habitat. Residency time is negatively correlated with distance to presumed source of colonizers. Farther sites are colonized last, from late Summer to Fall. Seven other tropical species, five of which closely related to H. charithonia, show a significantly similar distribution pattern in Texas suggesting a similar colonization pathway. With the expected changes in global climate, it is possible the advances and retreats shown by the tropical butterflies will be shifted northward. Long-term studies and historical data from naturalistic studies will help shed lights on this possibility.

Key words: Range shifts, Dispersal, Heliconiinae, Abiotic Factors

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