The flowerpiercers interactions with a community of high Andean plants

Background:Flowerpiercers(Diglossa)are traditionally considered as“parasites”of the pollination processes,as they can access the nectar without entering in contact with the reproductive structures of the plants.Nevertheless,the effect of flowerpiercers seems to vary according to their behavior and the flower’s traits.So,in this work,we aimed to explore the floral characteristics that may determine the susceptibility to robbing and pollen transport by flowerpierc-ers.Also,we identified the potential types of interactions and studied interaction network properties.Methods:We collected the information of 16 ornithophilic plants regarding their floral traits and robbing frequency.Also,we captured 4 species of flowerpiercers and evaluated pollen transport(frequency and loads).We tested the correlation between floral traits,robbing frequency,and pollen transportation.Later,we used these variables in a cluster and principal component analyses to identify the potential types of interactions.Finally,we analyzed and com-pared the structure of the plants-flowerpiercers interaction network.Results:Nectar production significantly influenced both nectar robbing and pollen transportation.While the corolla length was only correlated to the robbing susceptibility.Also,we found that particular flowerpiercers species trans-ported higher loads of some plant pollen,which can be related to the differences in behavior and morphometric traits.We proposed the classification of five different types of plant-flowerpiercer interactions,that showed differ-ent potential mutualist or antagonist relations based on the affectation of nectar robbing and the service of pollen transportation.The interaction networks consisted of 49 links,with 2.4 links per species,and presented indicators of a medium to high resilience,stability,and resistance(nestedness,connectance,and robustness).Also,the network presented medium to low specialization and substantial niche overlap.Conclusions:The ecological role of the flowerpiercers goes beyond its classic assignation as“parasites”as they can actively transport pollen of several Andean plants,affecting its evolutionary history and the stability of the systems.

Song divergence indicates an unclear relationship between the Neotropical and Nearctic Horned Larks

Background:Some studies have indicated that the Horned Larks(Eremophila alpestris)should be considered as a species complex.Recently it split into four species or clades and seven subclades based on genetic,morphological,and biogeographic data.However,other aspects like song divergence have not been studied and several subspe-cies have not been evaluated,leading to important information gaps in this group of birds.In this work,we aimed to assess the differences in song traits and playback response between the Nearctic subclade and the Neotropical or Colombian subspecies E.a.peregrina.Methods:We compared six song traits between these groups and performed field playback experiments,to test the response of the Neotropical larks to both songs.We tested the difference in the variables for separate as well as by principal component analysis(PCA).Results:We found significant differences(p<0.05)in the individual song traits and the PCA analysis between the two groups.Further,the PCA analysis showed a clearer divergence of the Neotropical songs in comparison to the Nearctic songs of different locations within North America.Similarly,the playback analysis showed a significantly lower response of E.a.peregrina to the songs of the Nearctic larks.Conclusions:Besides this song divergence,there are important ecological and biogeographic differences between the Neotropical and Nearctic Horned Larks,that indicate an unclear relationship between these two groups.Thus,further morphological and genetic studies are required to clarify the taxonomy of the Neotropical Horned Lark and define if they share the same evolutionary history as the other subspecies of the Nearctic subclade.