Chromosome microdissection is a technique in which whole chromosomes or chromosomal segments are dissected under an inverted microscope yielding chromosome-specific sequences. Several protocol modifications introduced during the past 15 years reduced the number of chromosomes required for most applications. This is of particular interest to fish molecular cytogenetics, since most species present highly uniform karyotypes which make impossible the collection of multiple copies of the same chromosome. Probes developed in this manner can be used to investigate chromosome homologies in closely related species. Here we describe a protocol recently used in the gymnotiform species group Eigenmannia and review the major steps involved in the generation of these markers focusing on protocol modifications aiming to reduce the number of required chromosomes.

O isolamento reprodutivo alocrônico parece ser um fator importante nos processos de especiação em Tephritidae, uma vez que a existência de horários de cópula específicos é uma característica comum de suas espécies. O horário de cópula de Anastrepha obliqua (Macquart) foi investigado usando observações segundo metodologia grupo-focal, durante dez dias, em condições de laboratório. O número de casais em cópula e de machos apresentando comportamento de chamado variou significativamente em relação ao horário do dia. As atividades sexuais mostraram-se concentradas no período vespertino, sendo que a chamada dos machos alcançou um pico entre 15:30h e 16:30h e as cópulas ocorreram mais freqüentemente entre as 14:00h e 16:30h.

Allochronic reproductive isolation seems to be an important factor in speciation processes in Tephritidae since specific mating times are a widespread feature of its species. The timing of matings of the West Indian fruit fly, Anastrepha obliqua (Macquart) was investigated through group-focal observations, during ten days, under laboratory conditions. The number of observed matings and males exhibiting calling behavior varied significantly according to time of day. Sexual activities seemed to be concentrated in the afternoon period, with the male calling behavior reaching a peak between 3:30p.m. and 4:30p.m., and mating occurred most frequently from 2:00p.m. to 4:30p.m.