Invasive chameleons released from predation display more conspicuous colors

Efficient and Highly Continuous Chromosome-Level Genome Assembly of the First Chameleon Genome

Most amniote genomes are diploid and moderate in size (∼1-6 Gbp) and contain a large proportion of repetitive sequences. The development of next-generation sequencing technology, especially the emergence of high-fidelity (HiFi) long-read data, has made it feasible to resolve high-quality genome assembly for nonmodel species efficiently. However, reference genomes for squamate reptiles have lagged behind other amniote lineages. Here, we de novo assembled the first genome from the Chameleonidae family, the panther chameleon (Furcifer pardalis). We obtained telomere-to-telomere contigs using only HiFi data, reaching a contig N50 of 158.72 Mbp. The final chromosome-level assembly is 1.61 Gbp in size, and 100% of primary contigs were placed to pseudochromosomes using Hi-C interaction data. We also found that sequencing depth > 30 folds can ensure both the integrity and accuracy of the genome, whereas insufficient depth led to false increase in genome size and proportion of duplicated genes. We provide a high-quality reference genome valuable for evolutionary and ecological studies in chameleons as well as provide comparative genomic resources for squamate reptiles.

Tactics of evasion: strategies used by signallers to deter eavesdropping enemies from exploiting communication systems

Eavesdropping predators, parasites and parasitoids exploit signals emitted by their prey and hosts for detection, assessment, localization and attack, and in the process impose strong selective pressures on the communication systems of the organisms they exploit. Signallers have evolved numerous anti-eavesdropper strategies to mitigate the trade-off between the costs imposed from signal exploitation and the need for conspecific communication. Eavesdropper strategies fall along a continuum from opportunistic to highly specialized, and the tightness of the eavesdropper-signaller relationship results in differential pressures on communication systems. A wide variety of anti-eavesdropper strategies mitigate the trade-off between eavesdropper exploitation and conspecific communication. Antagonistic selection from eavesdroppers can result in diverse outcomes including modulation of signalling displays, signal structure, and evolutionary loss or gain of a signal from a population. These strategies often result in reduced signal conspicuousness and in decreased signal ornamentation. Eavesdropping enemies, however, can also promote signal ornamentation. While less common, this alternative outcome offers a unique opportunity to dissect the factors that may lead to different evolutionary pathways. In addition, contrary to traditional assumptions, no sensory modality is completely 'safe' as eavesdroppers are ubiquitous and have a broad array of sensory filters that allow opportunity for signal exploitation. We discuss how anthropogenic change affects interactions between eavesdropping enemies and their victims as it rapidly modifies signalling environments and community composition. Drawing on diverse research from a range of taxa and sensory modalities, we synthesize current knowledge on anti-eavesdropper strategies, discuss challenges in this field and highlight fruitful new directions for future research. Ultimately, this review offers a conceptual framework to understand the diverse strategies used by signallers to communicate under the pressure imposed by their eavesdropping enemies.