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1. Biogeography confounds the signal of cospeciation in Batesian mimicry

   https://doi.org/10.1016/j.cub.2024.09.084  

   Van_Dam, Matthew H; Parisotto, Alessandro; Medina, Milton N; Cabras, Analyn A; Gutiérrez-Trejo, Nayeli; Wilts, Bodo D; Lam, Athena W (December 2024, Current Biology)

   Gemayel, Rita (Ed.)

   Since the inception of the field of evolution, mimicry has yielded insights into foundational evolutionary processes, including adaptive peak shifts, speciation, and the emergence and maintenance of phenotypic polymorphisms. In recent years, the coevolutionary processes generating mimicry have gained increasing attention from researchers. Despite significant advances in understanding Batesian and Müllerian mimicry in Lepidopteran systems, few other mimetic systems have received similar detailed research. Here, we present a Batesian mimicry complex involving flightless, armored Pachyrhynchus weevils and their winged Doliops longhorn beetle mimics and examine their coevolutionary patterns within the Philippine archipelagos. Pachyrhynchus weevils are primarily found in the Philippines, where distinct species radiations have occurred on different islands, each with unique color patterns serving as a warning to predators. This defensive trait and mimicry between unrelated species were first described by Wallace in 1889. Notably, the distantly related longhorn beetle Doliops, despite being soft-bodied and ostensibly palatable, mimics the heavily armored, flightless Pachyrhynchus. To address mimicry in this system, we reconstructed the phylogeny of Doliops using a probe set consisting of 38,000 ultraconserved elements. Our study examines the following questions central to understanding the Pachyrhynchus-Doliops mimicry system: (1) to what extent are coevolutionary interactions conserved (i.e., lineage-constrained) and (2) are the codiversification patterns primarily driven by biotic or abiotic factors? To assess color mimicry and cospeciation, we examined the evolution of nanostructure-based warning colors and the effect of island biogeography on cospeciation. Our findings demonstrate the beetle’s ability to repeatedly evolve multiple solutions to similar evolutionary challenges, evolving similar color patterns using different types of photonic crystals with varying degrees of order. We revealed that the observed pattern of cospeciation is driven mainly by abiotic factors from their biogeographic history. Unlike the patterns of coevolution seen between angiosperms and insect lineages, most ecological interactions do not persist longer than a few million years, leading to patterns of modularity rather than ecological nestedness 

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2. Balanced polymorphisms and their divergence in a Heliconius butterfly

   https://doi.org/10.1002/ece3.8423  

   Ogilvie, James_G; Van_Belleghem, Steven; Range, Ryan; Papa, Riccardo; McMillan, Owen_W; Chouteau, Mathieu; Counterman, Brian_A (December 2021, Ecology and Evolution)

   Abstract The evolution of mimicry in similarly defended prey is well described by the Müllerian mimicry theory, which predicts the convergence of warning patterns in order to gain the most protection from predators. However, despite this prediction, we can find great diversity of color patterns among Müllerian mimics such asHeliconiusbutterflies in the neotropics. Furthermore, some species have evolved the ability to maintain multiple distinct warning patterns in single populations, a phenomenon known as polymorphic mimicry. The adaptive benefit of these polymorphisms is questionable since variation from the most common warning patterns is expected to be disadvantageous as novel signals are punished by predators naive to them. In this study, we use artificial butterfly models throughout Central and South America to characterize the selective pressures maintaining polymorphic mimicry inHeliconius doris. Our results highlight the complexity of positive frequency‐dependent selection, the principal selective pressure driving convergence among Müllerian mimics, and its impacts on interspecific variation of mimetic warning coloration. We further show how this selection regime can both limit and facilitate the diversification of mimetic traits. 

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3. How the Easter Egg Weevils Got Their Spots: Phylogenomics Reveals Müllerian Mimicry in Pachyrhynchus (Coleoptera, Curculionidae)

   https://doi.org/10.1093/sysbio/syac064  

   Van Dam, Matthew H.; Anzano Cabras, Analyn; Lam, Athena W.; Moreau, ed., Corrie (September 2022, Systematic Biology)

   Abstract The evolutionary origins of mimicry in the Easter egg weevil, Pachyrhynchus, have fascinated researchers since first noted more than a century ago by Alfred Russel Wallace. Müllerian mimicry, or mimicry in which 2 or more distasteful species look similar, is widespread throughout the animal kingdom. Given the varied but discrete color patterns in Pachyrhynchus, this genus presents one of the best opportunities to study the evolution of both perfect and imperfect mimicry. We analyzed more than 10,000 UCE loci using a novel partitioning strategy to resolve the relationships of closely related species in the genus. Our results indicate that many of the mimetic color patterns observed in sympatric species are due to convergent evolution. We suggest that this convergence is driven by positive frequency-dependent selection. [Biogeography, discrete traits, frequency-dependent selection, mimicry, partitioning, Philippines, polymorphic, UCE.] 

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4. Combined measures of mimetic fidelity explain imperfect mimicry in a brood parasite–host system

   https://doi.org/10.1098/rsbl.2022.0538  

   Dixit, Tanmay; Choi, Gary P.; al-Mosleh, Salem; Lund, Jess; Troscianko, Jolyon; Moya, Collins; Mahadevan, L.; Spottiswoode, Claire N. (February 2023, Biology Letters)

   The persistence of imperfect mimicry in nature presents a challenge to mimicry theory. Some hypotheses for the existence of imperfect mimicry make differing predictions depending on how mimetic fidelity is measured. Here, we measure mimetic fidelity in a brood parasite–host system using both trait-based and response-based measures of mimetic fidelity. Cuckoo finchesAnomalospiza imberbislay imperfectly mimetic eggs that lack the fine scribbling characteristic of eggs of the tawny-flanked priniaPrinia subflava, a common host species. A trait-based discriminant analysis based on Minkowski functionals—that use geometric and topological morphometric methods related to egg pattern shape and coverage—reflects this consistent difference between host and parasite eggs. These methods could be applied to quantify other phenotypes including stripes and waved patterns. Furthermore, by painting scribbles onto cuckoo finch eggs and testing their rate of rejection compared to control eggs (i.e. a response-based approach to quantify mimetic fidelity), we show that prinias do not discriminate between eggs based on the absence of scribbles. Overall, our results support relaxed selection on cuckoo finches to mimic scribbles, since prinias do not respond differently to eggs with and without scribbles, despite the existence of this consistent trait difference. 

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5. How to make a red flower: the combinatorial effect of pigments

   https://doi.org/10.1093/aobpla/plw013  

   Ng, Julienne; Smith, Stacey D. (August 2015, AoB PLANTS)

   Abstract Red flowers have evolved repeatedly across angiosperms and are frequently examined in an ecological context. However, less is known about the biochemical basis of red colouration in different taxa. In this study, we examine the spectral properties, anthocyanin composition and carotenoid expression of red flowers in the tomato family, Solanaceae, which have evolved independently multiple times across the group. Our study demonstrates that Solanaceae typically make red flowers either by the sole production of red anthocyanins or, more commonly, by the dual production of purple or blue anthocyanins and orange carotenoids. In using carotenoids to modify the effect of purple and/or blue anthocyanins, these Solanaceae species have converged on the same floral hue as those solely producing red anthocyanins, even when considering the visual system of pollinators. The use of blue anthocyanins in red flowers appears to differ from other groups, and suggests that the genetic changes underlying evolutionary shifts to red flowers may not be as predictable as previously suggested. 

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