This thesis delves into the spectro-seismic connection observed in red giant stars, affirming that the necessary asteroseismic information for effectively discerning standard-candle red clump stars (RC) from non-standard-candle red giant branch (RGB) stars is embedded within their spectra. The objectives of this research are to, firstly, build upon prior investigations into the spectro-seismic connection of red giants by identifying the most informative spectral features indicative of their evolutionary state, spanning both the infrared and optical wavelengths, and secondly, to unravel the astrophysical mechanisms underlying this spectro-seismic connection. Utilising a data-driven approach with The Cannon, this study identifies key spectral features across two datasets. The first dataset comprises 49 red giants with moderate-resolution (R ∼ 10,000) VLT/X-Shooter spectra spanning a broad wavelength range in the optical and infrared (0.33 − 2.5 μ), while the second dataset includes 123 red giants with high-resolution Veloce Rosso spectra (R ∼ 80, 000; 5800 − 9500 Å). Both datasets are augmented with asteroseismic data from the K2 and TESS missions. Consistent with previous research, both studies highlight the significance of molecular features, particularly those related to carbon (e.g., CN, CH, CO), as the primary carriers of asteroseismic information in red giant spectra. Through an examination of CN isotopic pairs (12C14N and 13C14N) within the high-resolution sample of red giants with Veloce Rosso spectra, a statistically significant difference in the reduced equivalent widths of these lines was observed. This finding implies that physical mechanisms, such as deep mixing or the helium flash, which alter surface abundances and isotopic ratios in red giant stars, are the principal factors driving the spectro-seismic connection of red giants. In the concluding segment of this thesis, the informative spectral features from Veloce Rosso spectra were utilised to isolate a pristine sample of 155 RC stars. This selected sample was subsequently employed to investigate the chemodynamic characteristics of the Solar neighbourhood. The outcomes of this exploration corroborate findings from prior observational inquiries and exhibit close alignment with predictions derived from numerical simulations.