Data from: Condition-specific competition governs the geographic distribution and diversity of ectoparasites

Understanding how environmental parameters interact to govern species distributions is a shared goal of ecology and biogeography. Biotic and abiotic conditions can change distributions by affecting the nature of interspecific interactions. Although documented in free-living systems, this context dependency has been neglected in parasite interactions. We investigated the influence of condition-specific competition on the specificity of two species of feather lice (Phthiraptera: Ischnocera) that share a host, the mourning dove (Zenaida macroura). We show that relative humidity restricts the range of one species, Columbicola macrourae3 (i.e., the C. macrourae lineage found on mourning doves), to the more humid eastern United States. The second species, Columbicola baculoides, an arid-adapted species, is restricted to drier regions of the western United States by C. macrourae3, which outcompetes it in experiments. Thus, arid conditions in the West provide C. baculoides with a climatic refuge from the competitively superior C. macrourae3, effectively doubling parasite diversity on one host species. These results support the hypothesis that abiotic factors can determine species distributions on the stressful end of an environmental gradient while interspecific competition governs distributions at the benign end. The balance between these factors is subject to change as environmental conditions change, even if the host distribution remains unaffected.Louse populations at high and low humidity levelsThis file contains the population sizes of the two species of lice, C. macrourae3 and C. baculoides at the high and low humidity treatments in a captive animal experiment.humidityxlousespp_datafig2.txtPopulations of C. macrourae3 alone and sharing a hostThis file and the next file contain the population size data for the tests for the presence of competition between either louse species alone compared to sharing the host. The data has been split into a file for C. macrourae3 and one for C. baculoides data.mac_AD_NYM_compet_fig3.txtPopulations of C. baculoides alone and sharing a hostThis file and the previous file contain the population size data for the tests for the presence of competition between either louse species alone compared to sharing the host. The data has been split into a file for C. macrourae3 and one for C. baculoides data.bac_AD_NYM_compet_fig3.txtSurvival and reproduction of lice in incubator across humidity levelsThis file contains all the data for the incubator survival and reproduction experiments. It includes adult survival data, number of surviving nymphs per female, and number of eggs laid per female for both C. macrourae3 and C. baculoides at 4 different relative humidity levels (70%, 60%, 50% and 40%).incubat_adlt_nymph_eggs_fig4.txtChange in mass of C. macrourae3 and C. baculoides in incubatorThis file contains the data for the short-term weight loss trial in an incubator. It includes average weights for groups C. macourae3 and C. baculoides before and after time spent in a low humidity environment.incubator_masschange_fig5.tx